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* Re: [PATCH 1/2] remove all uses of printf's %n
       [not found]     ` <CAGXu5jK_D1BJOQr=1A-UFrpM5Ad+Qu894HT_XjkZh4EmsbCkTQ@mail.gmail.com>
@ 2013-09-20  4:09       ` Tetsuo Handa
  2013-09-20  4:23         ` Joe Perches
                           ` (2 more replies)
  0 siblings, 3 replies; 11+ messages in thread
From: Tetsuo Handa @ 2013-09-20  4:09 UTC (permalink / raw)
  To: jslaby, viro, xemul, remi.denis-courmont
  Cc: keescook, linux-kernel, netdev, linux-sctp, linux, akpm,
	dan.carpenter, geert, JBeulich, joe, kosaki.motohiro

Hello.

We are discussing about removal of %n support from vsnprintf() at
https://lkml.org/lkml/2013/9/16/52 , and you are using %n in seq_printf().

I posted https://lkml.org/lkml/diff/2013/9/19/53/1 which introduces
seq_setwidth() / seq_pad() which can avoid use of %n in seq_printf().
Assuming that this patch is merged, would you confirm that I didn't break
your code with below patch?

Regards.
----------------------------------------
>From f8b60ebe3971901b93dedb8eee0f85b60d0fdc5f Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Fri, 20 Sep 2013 12:01:07 +0900
Subject: [PATCH] Remove "%n" usage from seq_file users.

All seq_printf() users are using "%n" for calculating padding size, convert
them to use seq_setwidth() / seq_pad() pair.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 fs/proc/consoles.c   |   10 ++++------
 fs/proc/nommu.c      |   12 +++++-------
 fs/proc/task_mmu.c   |   20 ++++++--------------
 fs/proc/task_nommu.c |   19 ++++++-------------
 net/ipv4/fib_trie.c  |   13 +++++++------
 net/ipv4/ping.c      |   15 +++++++--------
 net/ipv4/tcp_ipv4.c  |   33 +++++++++++++++------------------
 net/ipv4/udp.c       |   15 +++++++--------
 net/phonet/socket.c  |   24 +++++++++++-------------
 net/sctp/objcnt.c    |    9 +++++----
 10 files changed, 73 insertions(+), 97 deletions(-)

diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index b701eaa..51942d5 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -29,7 +29,6 @@ static int show_console_dev(struct seq_file *m, void *v)
 	char flags[ARRAY_SIZE(con_flags) + 1];
 	struct console *con = v;
 	unsigned int a;
-	int len;
 	dev_t dev = 0;
 
 	if (con->device) {
@@ -47,11 +46,10 @@ static int show_console_dev(struct seq_file *m, void *v)
 			con_flags[a].name : ' ';
 	flags[a] = 0;
 
-	seq_printf(m, "%s%d%n", con->name, con->index, &len);
-	len = 21 - len;
-	if (len < 1)
-		len = 1;
-	seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
+	seq_setwidth(m, 21 - 1);
+	seq_printf(m, "%s%d", con->name, con->index);
+	seq_pad(m, ' ');
+	seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',
 			con->write ? 'W' : '-', con->unblank ? 'U' : '-',
 			flags);
 	if (dev)
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index ccfd99b..5f9bc8a 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -39,7 +39,7 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 	unsigned long ino = 0;
 	struct file *file;
 	dev_t dev = 0;
-	int flags, len;
+	int flags;
 
 	flags = region->vm_flags;
 	file = region->vm_file;
@@ -50,8 +50,9 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 		ino = inode->i_ino;
 	}
 
+	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
 	seq_printf(m,
-		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 		   region->vm_start,
 		   region->vm_end,
 		   flags & VM_READ ? 'r' : '-',
@@ -59,13 +60,10 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 		   flags & VM_EXEC ? 'x' : '-',
 		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
 		   ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
-		   MAJOR(dev), MINOR(dev), ino, &len);
+		   MAJOR(dev), MINOR(dev), ino);
 
 	if (file) {
-		len = 25 + sizeof(void *) * 6 - len;
-		if (len < 1)
-			len = 1;
-		seq_printf(m, "%*c", len, ' ');
+		seq_pad(m, ' ');
 		seq_path(m, &file->f_path, "");
 	}
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 7366e9d..cc24165 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -83,14 +83,6 @@ unsigned long task_statm(struct mm_struct *mm,
 	return mm->total_vm;
 }
 
-static void pad_len_spaces(struct seq_file *m, int len)
-{
-	len = 25 + sizeof(void*) * 6 - len;
-	if (len < 1)
-		len = 1;
-	seq_printf(m, "%*c", len, ' ');
-}
-
 #ifdef CONFIG_NUMA
 /*
  * These functions are for numa_maps but called in generic **maps seq_file
@@ -268,7 +260,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 	unsigned long long pgoff = 0;
 	unsigned long start, end;
 	dev_t dev = 0;
-	int len;
 	const char *name = NULL;
 
 	if (file) {
@@ -286,7 +277,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 	if (stack_guard_page_end(vma, end))
 		end -= PAGE_SIZE;
 
-	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
+	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 			start,
 			end,
 			flags & VM_READ ? 'r' : '-',
@@ -294,14 +286,14 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 			flags & VM_EXEC ? 'x' : '-',
 			flags & VM_MAYSHARE ? 's' : 'p',
 			pgoff,
-			MAJOR(dev), MINOR(dev), ino, &len);
+			MAJOR(dev), MINOR(dev), ino);
 
 	/*
 	 * Print the dentry name for named mappings, and a
 	 * special [heap] marker for the heap:
 	 */
 	if (file) {
-		pad_len_spaces(m, len);
+		seq_pad(m, ' ');
 		seq_path(m, &file->f_path, "\n");
 		goto done;
 	}
@@ -333,7 +325,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 				name = "[stack]";
 			} else {
 				/* Thread stack in /proc/PID/maps */
-				pad_len_spaces(m, len);
+				seq_pad(m, ' ');
 				seq_printf(m, "[stack:%d]", tid);
 			}
 		}
@@ -341,7 +333,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 
 done:
 	if (name) {
-		pad_len_spaces(m, len);
+		seq_pad(m, ' ');
 		seq_puts(m, name);
 	}
 	seq_putc(m, '\n');
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 56123a6..678455d 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -123,14 +123,6 @@ unsigned long task_statm(struct mm_struct *mm,
 	return size;
 }
 
-static void pad_len_spaces(struct seq_file *m, int len)
-{
-	len = 25 + sizeof(void*) * 6 - len;
-	if (len < 1)
-		len = 1;
-	seq_printf(m, "%*c", len, ' ');
-}
-
 /*
  * display a single VMA to a sequenced file
  */
@@ -142,7 +134,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 	unsigned long ino = 0;
 	struct file *file;
 	dev_t dev = 0;
-	int flags, len;
+	int flags;
 	unsigned long long pgoff = 0;
 
 	flags = vma->vm_flags;
@@ -155,8 +147,9 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 		pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
 	}
 
+	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
 	seq_printf(m,
-		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 		   vma->vm_start,
 		   vma->vm_end,
 		   flags & VM_READ ? 'r' : '-',
@@ -164,16 +157,16 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 		   flags & VM_EXEC ? 'x' : '-',
 		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
 		   pgoff,
-		   MAJOR(dev), MINOR(dev), ino, &len);
+		   MAJOR(dev), MINOR(dev), ino);
 
 	if (file) {
-		pad_len_spaces(m, len);
+		seq_pad(m, ' ');
 		seq_path(m, &file->f_path, "");
 	} else if (mm) {
 		pid_t tid = vm_is_stack(priv->task, vma, is_pid);
 
 		if (tid != 0) {
-			pad_len_spaces(m, len);
+			seq_pad(m, ' ');
 			/*
 			 * Thread stack in /proc/PID/task/TID/maps or
 			 * the main process stack.
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 3df6d3e..b1af50e 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2530,16 +2530,17 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
 		list_for_each_entry_rcu(fa, &li->falh, fa_list) {
 			const struct fib_info *fi = fa->fa_info;
 			unsigned int flags = fib_flag_trans(fa->fa_type, mask, fi);
-			int len;
 
 			if (fa->fa_type == RTN_BROADCAST
 			    || fa->fa_type == RTN_MULTICAST)
 				continue;
 
+			seq_setwidth(seq, 127);
+
 			if (fi)
 				seq_printf(seq,
 					 "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
-					 "%d\t%08X\t%d\t%u\t%u%n",
+					 "%d\t%08X\t%d\t%u\t%u",
 					 fi->fib_dev ? fi->fib_dev->name : "*",
 					 prefix,
 					 fi->fib_nh->nh_gw, flags, 0, 0,
@@ -2548,15 +2549,15 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
 					 (fi->fib_advmss ?
 					  fi->fib_advmss + 40 : 0),
 					 fi->fib_window,
-					 fi->fib_rtt >> 3, &len);
+					 fi->fib_rtt >> 3);
 			else
 				seq_printf(seq,
 					 "*\t%08X\t%08X\t%04X\t%d\t%u\t"
-					 "%d\t%08X\t%d\t%u\t%u%n",
+					 "%d\t%08X\t%d\t%u\t%u",
 					 prefix, 0, flags, 0, 0, 0,
-					 mask, 0, 0, 0, &len);
+					 mask, 0, 0, 0);
 
-			seq_printf(seq, "%*s\n", 127 - len, "");
+			seq_pad(seq, '\n');
 		}
 	}
 
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index d7d9882..94cc685 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -1073,7 +1073,7 @@ void ping_seq_stop(struct seq_file *seq, void *v)
 EXPORT_SYMBOL_GPL(ping_seq_stop);
 
 static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
-		int bucket, int *len)
+		int bucket)
 {
 	struct inet_sock *inet = inet_sk(sp);
 	__be32 dest = inet->inet_daddr;
@@ -1082,7 +1082,7 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
 	__u16 srcp = ntohs(inet->inet_sport);
 
 	seq_printf(f, "%5d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
@@ -1090,23 +1090,22 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp,
-		atomic_read(&sp->sk_drops), len);
+		atomic_read(&sp->sk_drops));
 }
 
 static int ping_v4_seq_show(struct seq_file *seq, void *v)
 {
+	seq_setwidth(seq, 127);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%-127s\n",
-			   "  sl  local_address rem_address   st tx_queue "
+		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
 			   "rx_queue tr tm->when retrnsmt   uid  timeout "
 			   "inode ref pointer drops");
 	else {
 		struct ping_iter_state *state = seq->private;
-		int len;
 
-		ping_v4_format_sock(v, seq, state->bucket, &len);
-		seq_printf(seq, "%*s\n", 127 - len, "");
+		ping_v4_format_sock(v, seq, state->bucket);
 	}
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b14266b..2948b76 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2598,13 +2598,13 @@ void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
 EXPORT_SYMBOL(tcp_proc_unregister);
 
 static void get_openreq4(const struct sock *sk, const struct request_sock *req,
-			 struct seq_file *f, int i, kuid_t uid, int *len)
+			 struct seq_file *f, int i, kuid_t uid)
 {
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	long delta = req->expires - jiffies;
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
 		i,
 		ireq->loc_addr,
 		ntohs(inet_sk(sk)->inet_sport),
@@ -2619,11 +2619,10 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
 		0,  /* non standard timer */
 		0, /* open_requests have no inode */
 		atomic_read(&sk->sk_refcnt),
-		req,
-		len);
+		req);
 }
 
-static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
+static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
 {
 	int timer_active;
 	unsigned long timer_expires;
@@ -2662,7 +2661,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
-			"%08X %5u %8d %lu %d %pK %lu %lu %u %u %d%n",
+			"%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
 		i, src, srcp, dest, destp, sk->sk_state,
 		tp->write_seq - tp->snd_una,
 		rx_queue,
@@ -2679,12 +2678,11 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		tp->snd_cwnd,
 		sk->sk_state == TCP_LISTEN ?
 		    (fastopenq ? fastopenq->max_qlen : 0) :
-		    (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh),
-		len);
+		    (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
 }
 
 static void get_timewait4_sock(const struct inet_timewait_sock *tw,
-			       struct seq_file *f, int i, int *len)
+			       struct seq_file *f, int i)
 {
 	__be32 dest, src;
 	__u16 destp, srcp;
@@ -2696,10 +2694,10 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 	srcp  = ntohs(tw->tw_sport);
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
 		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
 		3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
-		atomic_read(&tw->tw_refcnt), tw, len);
+		atomic_read(&tw->tw_refcnt), tw);
 }
 
 #define TMPSZ 150
@@ -2707,11 +2705,10 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 static int tcp4_seq_show(struct seq_file *seq, void *v)
 {
 	struct tcp_iter_state *st;
-	int len;
 
+	seq_setwidth(seq, TMPSZ - 1);
 	if (v == SEQ_START_TOKEN) {
-		seq_printf(seq, "%-*s\n", TMPSZ - 1,
-			   "  sl  local_address rem_address   st tx_queue "
+		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
 			   "rx_queue tr tm->when retrnsmt   uid  timeout "
 			   "inode");
 		goto out;
@@ -2721,17 +2718,17 @@ static int tcp4_seq_show(struct seq_file *seq, void *v)
 	switch (st->state) {
 	case TCP_SEQ_STATE_LISTENING:
 	case TCP_SEQ_STATE_ESTABLISHED:
-		get_tcp4_sock(v, seq, st->num, &len);
+		get_tcp4_sock(v, seq, st->num);
 		break;
 	case TCP_SEQ_STATE_OPENREQ:
-		get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
+		get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid);
 		break;
 	case TCP_SEQ_STATE_TIME_WAIT:
-		get_timewait4_sock(v, seq, st->num, &len);
+		get_timewait4_sock(v, seq, st->num);
 		break;
 	}
-	seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
 out:
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 74d2c95..31c132c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2150,7 +2150,7 @@ EXPORT_SYMBOL(udp_proc_unregister);
 
 /* ------------------------------------------------------------------------ */
 static void udp4_format_sock(struct sock *sp, struct seq_file *f,
-		int bucket, int *len)
+		int bucket)
 {
 	struct inet_sock *inet = inet_sk(sp);
 	__be32 dest = inet->inet_daddr;
@@ -2159,7 +2159,7 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 	__u16 srcp	  = ntohs(inet->inet_sport);
 
 	seq_printf(f, "%5d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
@@ -2167,23 +2167,22 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp,
-		atomic_read(&sp->sk_drops), len);
+		atomic_read(&sp->sk_drops));
 }
 
 int udp4_seq_show(struct seq_file *seq, void *v)
 {
+	seq_setwidth(seq, 127);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%-127s\n",
-			   "  sl  local_address rem_address   st tx_queue "
+		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
 			   "rx_queue tr tm->when retrnsmt   uid  timeout "
 			   "inode ref pointer drops");
 	else {
 		struct udp_iter_state *state = seq->private;
-		int len;
 
-		udp4_format_sock(v, seq, state->bucket, &len);
-		seq_printf(seq, "%*s\n", 127 - len, "");
+		udp4_format_sock(v, seq, state->bucket);
 	}
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index 77e38f7..008214a 100644
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -595,26 +595,25 @@ static void pn_sock_seq_stop(struct seq_file *seq, void *v)
 
 static int pn_sock_seq_show(struct seq_file *seq, void *v)
 {
-	int len;
-
+	seq_setwidth(seq, 127);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%s%n", "pt  loc  rem rs st tx_queue rx_queue "
-			"  uid inode ref pointer drops", &len);
+		seq_puts(seq, "pt  loc  rem rs st tx_queue rx_queue "
+			"  uid inode ref pointer drops");
 	else {
 		struct sock *sk = v;
 		struct pn_sock *pn = pn_sk(sk);
 
 		seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
-			"%d %pK %d%n",
+			"%d %pK %d",
 			sk->sk_protocol, pn->sobject, pn->dobject,
 			pn->resource, sk->sk_state,
 			sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
 			from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
 			sock_i_ino(sk),
 			atomic_read(&sk->sk_refcnt), sk,
-			atomic_read(&sk->sk_drops), &len);
+			atomic_read(&sk->sk_drops));
 	}
-	seq_printf(seq, "%*s\n", 127 - len, "");
+	seq_pad(seq, '\n');
 	return 0;
 }
 
@@ -785,20 +784,19 @@ static void pn_res_seq_stop(struct seq_file *seq, void *v)
 
 static int pn_res_seq_show(struct seq_file *seq, void *v)
 {
-	int len;
-
+	seq_setwidth(seq, 63);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%s%n", "rs   uid inode", &len);
+		seq_puts(seq, "rs   uid inode");
 	else {
 		struct sock **psk = v;
 		struct sock *sk = *psk;
 
-		seq_printf(seq, "%02X %5u %lu%n",
+		seq_printf(seq, "%02X %5u %lu",
 			   (int) (psk - pnres.sk),
 			   from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
-			   sock_i_ino(sk), &len);
+			   sock_i_ino(sk));
 	}
-	seq_printf(seq, "%*s\n", 63 - len, "");
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/sctp/objcnt.c b/net/sctp/objcnt.c
index 5ea573b..647396b 100644
--- a/net/sctp/objcnt.c
+++ b/net/sctp/objcnt.c
@@ -79,12 +79,13 @@ static sctp_dbg_objcnt_entry_t sctp_dbg_objcnt[] = {
  */
 static int sctp_objcnt_seq_show(struct seq_file *seq, void *v)
 {
-	int i, len;
+	int i;
 
 	i = (int)*(loff_t *)v;
-	seq_printf(seq, "%s: %d%n", sctp_dbg_objcnt[i].label,
-				atomic_read(sctp_dbg_objcnt[i].counter), &len);
-	seq_printf(seq, "%*s\n", 127 - len, "");
+	seq_setwidth(seq, 127);
+	seq_printf(seq, "%s: %d", sctp_dbg_objcnt[i].label,
+				atomic_read(sctp_dbg_objcnt[i].counter));
+	seq_pad(seq, '\n');
 	return 0;
 }
 
-- 
1.7.1

^ permalink raw reply related	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20  4:09       ` [PATCH 1/2] remove all uses of printf's %n Tetsuo Handa
@ 2013-09-20  4:23         ` Joe Perches
  2013-09-20  4:53           ` Kees Cook
  2013-09-20  8:08         ` Jiri Slaby
  2013-09-23 21:24         ` Kees Cook
  2 siblings, 1 reply; 11+ messages in thread
From: Joe Perches @ 2013-09-20  4:23 UTC (permalink / raw)
  To: Tetsuo Handa
  Cc: jslaby, viro, xemul, remi.denis-courmont, keescook, linux-kernel,
	netdev, linux-sctp, linux, akpm, dan.carpenter, geert, JBeulich,
	kosaki.motohiro

On Fri, 2013-09-20 at 13:09 +0900, Tetsuo Handa wrote:
> Hello.

Tetsuo-san:

> We are discussing about removal of %n support from vsnprintf() at
> https://lkml.org/lkml/2013/9/16/52 , and you are using %n in seq_printf().

Well, I'm not using (mere alcohol isn't using, right?)
but I still have the same question for Al.

Are there any races here?

> I posted https://lkml.org/lkml/diff/2013/9/19/53/1 which introduces
> seq_setwidth() / seq_pad() which can avoid use of %n in seq_printf().

I still think adding last_len, last_rtn
is sensible.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20  4:23         ` Joe Perches
@ 2013-09-20  4:53           ` Kees Cook
  0 siblings, 0 replies; 11+ messages in thread
From: Kees Cook @ 2013-09-20  4:53 UTC (permalink / raw)
  To: Joe Perches
  Cc: Tetsuo Handa, Jiri Slaby, Al Viro, Pavel Emelyanov,
	remi.denis-courmont, LKML, netdev, linux-sctp, George Spelvin,
	Andrew Morton, Dan Carpenter, Geert Uytterhoeven, Jan Beulich,
	Motohiro KOSAKI

On Thu, Sep 19, 2013 at 9:23 PM, Joe Perches <joe@perches.com> wrote:
> On Fri, 2013-09-20 at 13:09 +0900, Tetsuo Handa wrote:
>> Hello.
>
> Tetsuo-san:
>
>> We are discussing about removal of %n support from vsnprintf() at
>> https://lkml.org/lkml/2013/9/16/52 , and you are using %n in seq_printf().
>
> Well, I'm not using (mere alcohol isn't using, right?)
> but I still have the same question for Al.
>
> Are there any races here?

All the call sites I examined were linear. FWIW, I didn't see any races.

-Kees

>
>> I posted https://lkml.org/lkml/diff/2013/9/19/53/1 which introduces
>> seq_setwidth() / seq_pad() which can avoid use of %n in seq_printf().
>
> I still think adding last_len, last_rtn
> is sensible.
>
>



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20  4:09       ` [PATCH 1/2] remove all uses of printf's %n Tetsuo Handa
  2013-09-20  4:23         ` Joe Perches
@ 2013-09-20  8:08         ` Jiri Slaby
  2013-09-20 19:24           ` Kees Cook
  2013-09-23 21:24         ` Kees Cook
  2 siblings, 1 reply; 11+ messages in thread
From: Jiri Slaby @ 2013-09-20  8:08 UTC (permalink / raw)
  To: Tetsuo Handa, viro, xemul, remi.denis-courmont
  Cc: keescook, linux-kernel, netdev, linux-sctp, linux, akpm,
	dan.carpenter, geert, JBeulich, joe, kosaki.motohiro

On 09/20/2013 06:09 AM, Tetsuo Handa wrote:
> --- a/fs/proc/consoles.c
> +++ b/fs/proc/consoles.c
...
> @@ -47,11 +46,10 @@ static int show_console_dev(struct seq_file *m, void *v)
>  			con_flags[a].name : ' ';
>  	flags[a] = 0;
>  
> -	seq_printf(m, "%s%d%n", con->name, con->index, &len);
> -	len = 21 - len;
> -	if (len < 1)
> -		len = 1;
> -	seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
> +	seq_setwidth(m, 21 - 1);
> +	seq_printf(m, "%s%d", con->name, con->index);
> +	seq_pad(m, ' ');
> +	seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',
>  			con->write ? 'W' : '-', con->unblank ? 'U' : '-',
>  			flags);

Hello, do you really need seq_setwidth? It makes it really ugly...

Or do we need that all? Couldn't we simply have seq_printf_padded? Or
maybe some % modifier in seq_printf to pad the string?

> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
...
> @@ -2548,15 +2549,15 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
>  					 (fi->fib_advmss ?
>  					  fi->fib_advmss + 40 : 0),
>  					 fi->fib_window,
> -					 fi->fib_rtt >> 3, &len);
> +					 fi->fib_rtt >> 3);
>  			else
>  				seq_printf(seq,
>  					 "*\t%08X\t%08X\t%04X\t%d\t%u\t"
> -					 "%d\t%08X\t%d\t%u\t%u%n",
> +					 "%d\t%08X\t%d\t%u\t%u",
>  					 prefix, 0, flags, 0, 0, 0,
> -					 mask, 0, 0, 0, &len);
> +					 mask, 0, 0, 0);
>  
> -			seq_printf(seq, "%*s\n", 127 - len, "");
> +			seq_pad(seq, '\n');

Hmm, seq_pad is unintuitive. I would say it pads the string by '\n'. Of
course it does not, but...

thanks,
-- 
js
suse labs

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20  8:08         ` Jiri Slaby
@ 2013-09-20 19:24           ` Kees Cook
  2013-09-20 19:33             ` Joe Perches
  2013-09-21  0:28             ` Tetsuo Handa
  0 siblings, 2 replies; 11+ messages in thread
From: Kees Cook @ 2013-09-20 19:24 UTC (permalink / raw)
  To: Jiri Slaby
  Cc: Tetsuo Handa, Al Viro, Pavel Emelyanov, Rémi Denis-Courmont,
	LKML, netdev, linux-sctp, George Spelvin, Andrew Morton,
	Dan Carpenter, Geert Uytterhoeven, Jan Beulich, Joe Perches,
	Motohiro KOSAKI

On Fri, Sep 20, 2013 at 1:08 AM, Jiri Slaby <jslaby@suse.cz> wrote:
> On 09/20/2013 06:09 AM, Tetsuo Handa wrote:
>> --- a/fs/proc/consoles.c
>> +++ b/fs/proc/consoles.c
> ...
>> @@ -47,11 +46,10 @@ static int show_console_dev(struct seq_file *m, void *v)
>>                       con_flags[a].name : ' ';
>>       flags[a] = 0;
>>
>> -     seq_printf(m, "%s%d%n", con->name, con->index, &len);
>> -     len = 21 - len;
>> -     if (len < 1)
>> -             len = 1;
>> -     seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
>> +     seq_setwidth(m, 21 - 1);
>> +     seq_printf(m, "%s%d", con->name, con->index);
>> +     seq_pad(m, ' ');
>> +     seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',
>>                       con->write ? 'W' : '-', con->unblank ? 'U' : '-',
>>                       flags);
>
> Hello, do you really need seq_setwidth? It makes it really ugly...

There are a few problems that have been discussed on the various
threads. Namely, we want to minimize the changes to the seq_file
structure and to not add additional work to all the seq_file users
that don't care about padding. If the seq_file calls always track how
far they're written across each call, we add unneeded work to all the
users. To avoid this, we must identify to the seq_file subsystem where
we want to start tracking the length written. To allow this to be
spread across multiple calls (something the %n can't do), we must
record seq->count at some point, and then compare against it at the
point where we want to perform padding.

> Or do we need that all? Couldn't we simply have seq_printf_padded? Or
> maybe some % modifier in seq_printf to pad the string?

Adding a _padding version of things means we'd have to add it to all
seq_* function that print things (like printing paths, etc). Using
this method, the output doesn't matter. We declare the starting point,
output whatever we need, then perform padding, and continue writing.

I think the declaration/output/pad method seems the least invasive to
existing users of padding, and the highest level of flexibility going
forward for future users.

>> --- a/net/ipv4/fib_trie.c
>> +++ b/net/ipv4/fib_trie.c
> ...
>> @@ -2548,15 +2549,15 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
>>                                        (fi->fib_advmss ?
>>                                         fi->fib_advmss + 40 : 0),
>>                                        fi->fib_window,
>> -                                      fi->fib_rtt >> 3, &len);
>> +                                      fi->fib_rtt >> 3);
>>                       else
>>                               seq_printf(seq,
>>                                        "*\t%08X\t%08X\t%04X\t%d\t%u\t"
>> -                                      "%d\t%08X\t%d\t%u\t%u%n",
>> +                                      "%d\t%08X\t%d\t%u\t%u",
>>                                        prefix, 0, flags, 0, 0, 0,
>> -                                      mask, 0, 0, 0, &len);
>> +                                      mask, 0, 0, 0);
>>
>> -                     seq_printf(seq, "%*s\n", 127 - len, "");
>> +                     seq_pad(seq, '\n');
>
> Hmm, seq_pad is unintuitive. I would say it pads the string by '\n'. Of
> course it does not, but...

I don't think this is a very serious problem. Currently, the padding
character is always ' ' for all existing callers, so it only makes
sense to make the trailing character an argument.

-Kees

-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20 19:24           ` Kees Cook
@ 2013-09-20 19:33             ` Joe Perches
  2013-09-21  0:28             ` Tetsuo Handa
  1 sibling, 0 replies; 11+ messages in thread
From: Joe Perches @ 2013-09-20 19:33 UTC (permalink / raw)
  To: Kees Cook
  Cc: Jiri Slaby, Tetsuo Handa, Al Viro, Pavel Emelyanov,
	Rémi Denis-Courmont, LKML, netdev, linux-sctp,
	George Spelvin, Andrew Morton, Dan Carpenter, Geert Uytterhoeven,
	Jan Beulich, Motohiro KOSAKI

On Fri, 2013-09-20 at 12:24 -0700, Kees Cook wrote:
> There are a few problems that have been discussed on the various
> threads. Namely, we want to minimize the changes to the seq_file
> structure and to not add additional work to all the seq_file users
> that don't care about padding.

I don't think saving a couple more values to a struct
is that big a deal.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20 19:24           ` Kees Cook
  2013-09-20 19:33             ` Joe Perches
@ 2013-09-21  0:28             ` Tetsuo Handa
  2013-09-22  8:09               ` George Spelvin
  2013-09-22  8:16               ` Geert Uytterhoeven
  1 sibling, 2 replies; 11+ messages in thread
From: Tetsuo Handa @ 2013-09-21  0:28 UTC (permalink / raw)
  To: keescook, jslaby
  Cc: viro, xemul, remi.denis-courmont, linux-kernel, netdev,
	linux-sctp, linux, akpm, dan.carpenter, geert, JBeulich, joe,
	kosaki.motohiro

Kees Cook wrote:
> >> -                     seq_printf(seq, "%*s\n", 127 - len, "");
> >> +                     seq_pad(seq, '\n');
> >
> > Hmm, seq_pad is unintuitive. I would say it pads the string by '\n'. Of
> > course it does not, but...
> 
> I don't think this is a very serious problem. Currently, the padding
> character is always ' ' for all existing callers, so it only makes
> sense to make the trailing character an argument.

If you want, we can rename seq_pad() to seq_pad_and_putc(). Also we can pass
both the padding character (e.g. ' ') and the trailing character (e.g. '\n')
like seq_pad_and_putc((' ' << 8) | '\n'), though I wonder someone wants to
use '\0', '\t', '\n' etc. as the padding character...

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-21  0:28             ` Tetsuo Handa
@ 2013-09-22  8:09               ` George Spelvin
  2013-09-22  8:16               ` Geert Uytterhoeven
  1 sibling, 0 replies; 11+ messages in thread
From: George Spelvin @ 2013-09-22  8:09 UTC (permalink / raw)
  To: jslaby, keescook, penguin-kernel
  Cc: akpm, dan.carpenter, geert, JBeulich, joe, kosaki.motohiro,
	linux-kernel, linux-sctp, linux, netdev, remi.denis-courmont,
	viro, xemul

> If you want, we can rename seq_pad() to seq_pad_and_putc(). Also we can pass
> both the padding character (e.g. ' ') and the trailing character (e.g. '\n')
> like seq_pad_and_putc((' ' << 8) | '\n'), though I wonder someone wants to
> use '\0', '\t', '\n' etc. as the padding character...

How about let that complexity wait until it's needed?  It's not like
it's that big a PITA of a patch to write, and there's a significant
chance it will *never* be needed.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-21  0:28             ` Tetsuo Handa
  2013-09-22  8:09               ` George Spelvin
@ 2013-09-22  8:16               ` Geert Uytterhoeven
  1 sibling, 0 replies; 11+ messages in thread
From: Geert Uytterhoeven @ 2013-09-22  8:16 UTC (permalink / raw)
  To: Tetsuo Handa
  Cc: Kees Cook, Jiri Slaby, Al Viro, xemul, remi.denis-courmont,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-sctp,
	George Spelvin, Andrew Morton, Dan Carpenter, Jan Beulich,
	Joe Perches, Motohiro KOSAKI

On Sat, Sep 21, 2013 at 2:28 AM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> Kees Cook wrote:
>> >> -                     seq_printf(seq, "%*s\n", 127 - len, "");
>> >> +                     seq_pad(seq, '\n');
>> >
>> > Hmm, seq_pad is unintuitive. I would say it pads the string by '\n'. Of
>> > course it does not, but...
>>
>> I don't think this is a very serious problem. Currently, the padding
>> character is always ' ' for all existing callers, so it only makes
>> sense to make the trailing character an argument.
>
> If you want, we can rename seq_pad() to seq_pad_and_putc(). Also we can pass
> both the padding character (e.g. ' ') and the trailing character (e.g. '\n')
> like seq_pad_and_putc((' ' << 8) | '\n'), though I wonder someone wants to
> use '\0', '\t', '\n' etc. as the padding character...

Not those special characters. '-' could be useful for tables (doh,
text-mode graphics
log output).

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-20  4:09       ` [PATCH 1/2] remove all uses of printf's %n Tetsuo Handa
  2013-09-20  4:23         ` Joe Perches
  2013-09-20  8:08         ` Jiri Slaby
@ 2013-09-23 21:24         ` Kees Cook
  2013-09-30  8:16           ` Tetsuo Handa
  2 siblings, 1 reply; 11+ messages in thread
From: Kees Cook @ 2013-09-23 21:24 UTC (permalink / raw)
  To: Tetsuo Handa, Andrew Morton
  Cc: Jiri Slaby, Al Viro, Pavel Emelyanov, LKML, netdev, linux-sctp,
	George Spelvin, Dan Carpenter, Geert Uytterhoeven, Jan Beulich,
	Joe Perches, Motohiro KOSAKI

[-remi (bouncing), +akpm]

On Thu, Sep 19, 2013 at 9:09 PM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> Hello.
>
> We are discussing about removal of %n support from vsnprintf() at
> https://lkml.org/lkml/2013/9/16/52 , and you are using %n in seq_printf().
>
> I posted https://lkml.org/lkml/diff/2013/9/19/53/1 which introduces
> seq_setwidth() / seq_pad() which can avoid use of %n in seq_printf().
> Assuming that this patch is merged, would you confirm that I didn't break
> your code with below patch?

As mentioned in the thread, I think we should carry this with the
patch that adds seq_pad and drops %n. It's the cleanest of the
solutions, adds no CPU overhead to other seq_file users, addresses the
basic need (seq_printf padding) while providing expanded functionality
(tracking padding for any seq_file writes, not just seq_printf).

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

>
> Regards.
> ----------------------------------------
> >From f8b60ebe3971901b93dedb8eee0f85b60d0fdc5f Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Date: Fri, 20 Sep 2013 12:01:07 +0900
> Subject: [PATCH] Remove "%n" usage from seq_file users.
>
> All seq_printf() users are using "%n" for calculating padding size, convert
> them to use seq_setwidth() / seq_pad() pair.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
>  fs/proc/consoles.c   |   10 ++++------
>  fs/proc/nommu.c      |   12 +++++-------
>  fs/proc/task_mmu.c   |   20 ++++++--------------
>  fs/proc/task_nommu.c |   19 ++++++-------------
>  net/ipv4/fib_trie.c  |   13 +++++++------
>  net/ipv4/ping.c      |   15 +++++++--------
>  net/ipv4/tcp_ipv4.c  |   33 +++++++++++++++------------------
>  net/ipv4/udp.c       |   15 +++++++--------
>  net/phonet/socket.c  |   24 +++++++++++-------------
>  net/sctp/objcnt.c    |    9 +++++----
>  10 files changed, 73 insertions(+), 97 deletions(-)
>
> diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
> index b701eaa..51942d5 100644
> --- a/fs/proc/consoles.c
> +++ b/fs/proc/consoles.c
> @@ -29,7 +29,6 @@ static int show_console_dev(struct seq_file *m, void *v)
>         char flags[ARRAY_SIZE(con_flags) + 1];
>         struct console *con = v;
>         unsigned int a;
> -       int len;
>         dev_t dev = 0;
>
>         if (con->device) {
> @@ -47,11 +46,10 @@ static int show_console_dev(struct seq_file *m, void *v)
>                         con_flags[a].name : ' ';
>         flags[a] = 0;
>
> -       seq_printf(m, "%s%d%n", con->name, con->index, &len);
> -       len = 21 - len;
> -       if (len < 1)
> -               len = 1;
> -       seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
> +       seq_setwidth(m, 21 - 1);
> +       seq_printf(m, "%s%d", con->name, con->index);
> +       seq_pad(m, ' ');
> +       seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',
>                         con->write ? 'W' : '-', con->unblank ? 'U' : '-',
>                         flags);
>         if (dev)
> diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
> index ccfd99b..5f9bc8a 100644
> --- a/fs/proc/nommu.c
> +++ b/fs/proc/nommu.c
> @@ -39,7 +39,7 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
>         unsigned long ino = 0;
>         struct file *file;
>         dev_t dev = 0;
> -       int flags, len;
> +       int flags;
>
>         flags = region->vm_flags;
>         file = region->vm_file;
> @@ -50,8 +50,9 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
>                 ino = inode->i_ino;
>         }
>
> +       seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
>         seq_printf(m,
> -                  "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
> +                  "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
>                    region->vm_start,
>                    region->vm_end,
>                    flags & VM_READ ? 'r' : '-',
> @@ -59,13 +60,10 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
>                    flags & VM_EXEC ? 'x' : '-',
>                    flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
>                    ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
> -                  MAJOR(dev), MINOR(dev), ino, &len);
> +                  MAJOR(dev), MINOR(dev), ino);
>
>         if (file) {
> -               len = 25 + sizeof(void *) * 6 - len;
> -               if (len < 1)
> -                       len = 1;
> -               seq_printf(m, "%*c", len, ' ');
> +               seq_pad(m, ' ');
>                 seq_path(m, &file->f_path, "");
>         }
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 7366e9d..cc24165 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -83,14 +83,6 @@ unsigned long task_statm(struct mm_struct *mm,
>         return mm->total_vm;
>  }
>
> -static void pad_len_spaces(struct seq_file *m, int len)
> -{
> -       len = 25 + sizeof(void*) * 6 - len;
> -       if (len < 1)
> -               len = 1;
> -       seq_printf(m, "%*c", len, ' ');
> -}
> -
>  #ifdef CONFIG_NUMA
>  /*
>   * These functions are for numa_maps but called in generic **maps seq_file
> @@ -268,7 +260,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
>         unsigned long long pgoff = 0;
>         unsigned long start, end;
>         dev_t dev = 0;
> -       int len;
>         const char *name = NULL;
>
>         if (file) {
> @@ -286,7 +277,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
>         if (stack_guard_page_end(vma, end))
>                 end -= PAGE_SIZE;
>
> -       seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
> +       seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
> +       seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
>                         start,
>                         end,
>                         flags & VM_READ ? 'r' : '-',
> @@ -294,14 +286,14 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
>                         flags & VM_EXEC ? 'x' : '-',
>                         flags & VM_MAYSHARE ? 's' : 'p',
>                         pgoff,
> -                       MAJOR(dev), MINOR(dev), ino, &len);
> +                       MAJOR(dev), MINOR(dev), ino);
>
>         /*
>          * Print the dentry name for named mappings, and a
>          * special [heap] marker for the heap:
>          */
>         if (file) {
> -               pad_len_spaces(m, len);
> +               seq_pad(m, ' ');
>                 seq_path(m, &file->f_path, "\n");
>                 goto done;
>         }
> @@ -333,7 +325,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
>                                 name = "[stack]";
>                         } else {
>                                 /* Thread stack in /proc/PID/maps */
> -                               pad_len_spaces(m, len);
> +                               seq_pad(m, ' ');
>                                 seq_printf(m, "[stack:%d]", tid);
>                         }
>                 }
> @@ -341,7 +333,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
>
>  done:
>         if (name) {
> -               pad_len_spaces(m, len);
> +               seq_pad(m, ' ');
>                 seq_puts(m, name);
>         }
>         seq_putc(m, '\n');
> diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
> index 56123a6..678455d 100644
> --- a/fs/proc/task_nommu.c
> +++ b/fs/proc/task_nommu.c
> @@ -123,14 +123,6 @@ unsigned long task_statm(struct mm_struct *mm,
>         return size;
>  }
>
> -static void pad_len_spaces(struct seq_file *m, int len)
> -{
> -       len = 25 + sizeof(void*) * 6 - len;
> -       if (len < 1)
> -               len = 1;
> -       seq_printf(m, "%*c", len, ' ');
> -}
> -
>  /*
>   * display a single VMA to a sequenced file
>   */
> @@ -142,7 +134,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
>         unsigned long ino = 0;
>         struct file *file;
>         dev_t dev = 0;
> -       int flags, len;
> +       int flags;
>         unsigned long long pgoff = 0;
>
>         flags = vma->vm_flags;
> @@ -155,8 +147,9 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
>                 pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
>         }
>
> +       seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
>         seq_printf(m,
> -                  "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
> +                  "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
>                    vma->vm_start,
>                    vma->vm_end,
>                    flags & VM_READ ? 'r' : '-',
> @@ -164,16 +157,16 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
>                    flags & VM_EXEC ? 'x' : '-',
>                    flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
>                    pgoff,
> -                  MAJOR(dev), MINOR(dev), ino, &len);
> +                  MAJOR(dev), MINOR(dev), ino);
>
>         if (file) {
> -               pad_len_spaces(m, len);
> +               seq_pad(m, ' ');
>                 seq_path(m, &file->f_path, "");
>         } else if (mm) {
>                 pid_t tid = vm_is_stack(priv->task, vma, is_pid);
>
>                 if (tid != 0) {
> -                       pad_len_spaces(m, len);
> +                       seq_pad(m, ' ');
>                         /*
>                          * Thread stack in /proc/PID/task/TID/maps or
>                          * the main process stack.
> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> index 3df6d3e..b1af50e 100644
> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
> @@ -2530,16 +2530,17 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
>                 list_for_each_entry_rcu(fa, &li->falh, fa_list) {
>                         const struct fib_info *fi = fa->fa_info;
>                         unsigned int flags = fib_flag_trans(fa->fa_type, mask, fi);
> -                       int len;
>
>                         if (fa->fa_type == RTN_BROADCAST
>                             || fa->fa_type == RTN_MULTICAST)
>                                 continue;
>
> +                       seq_setwidth(seq, 127);
> +
>                         if (fi)
>                                 seq_printf(seq,
>                                          "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
> -                                        "%d\t%08X\t%d\t%u\t%u%n",
> +                                        "%d\t%08X\t%d\t%u\t%u",
>                                          fi->fib_dev ? fi->fib_dev->name : "*",
>                                          prefix,
>                                          fi->fib_nh->nh_gw, flags, 0, 0,
> @@ -2548,15 +2549,15 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
>                                          (fi->fib_advmss ?
>                                           fi->fib_advmss + 40 : 0),
>                                          fi->fib_window,
> -                                        fi->fib_rtt >> 3, &len);
> +                                        fi->fib_rtt >> 3);
>                         else
>                                 seq_printf(seq,
>                                          "*\t%08X\t%08X\t%04X\t%d\t%u\t"
> -                                        "%d\t%08X\t%d\t%u\t%u%n",
> +                                        "%d\t%08X\t%d\t%u\t%u",
>                                          prefix, 0, flags, 0, 0, 0,
> -                                        mask, 0, 0, 0, &len);
> +                                        mask, 0, 0, 0);
>
> -                       seq_printf(seq, "%*s\n", 127 - len, "");
> +                       seq_pad(seq, '\n');
>                 }
>         }
>
> diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> index d7d9882..94cc685 100644
> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -1073,7 +1073,7 @@ void ping_seq_stop(struct seq_file *seq, void *v)
>  EXPORT_SYMBOL_GPL(ping_seq_stop);
>
>  static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
> -               int bucket, int *len)
> +               int bucket)
>  {
>         struct inet_sock *inet = inet_sk(sp);
>         __be32 dest = inet->inet_daddr;
> @@ -1082,7 +1082,7 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
>         __u16 srcp = ntohs(inet->inet_sport);
>
>         seq_printf(f, "%5d: %08X:%04X %08X:%04X"
> -               " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
> +               " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
>                 bucket, src, srcp, dest, destp, sp->sk_state,
>                 sk_wmem_alloc_get(sp),
>                 sk_rmem_alloc_get(sp),
> @@ -1090,23 +1090,22 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
>                 from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
>                 0, sock_i_ino(sp),
>                 atomic_read(&sp->sk_refcnt), sp,
> -               atomic_read(&sp->sk_drops), len);
> +               atomic_read(&sp->sk_drops));
>  }
>
>  static int ping_v4_seq_show(struct seq_file *seq, void *v)
>  {
> +       seq_setwidth(seq, 127);
>         if (v == SEQ_START_TOKEN)
> -               seq_printf(seq, "%-127s\n",
> -                          "  sl  local_address rem_address   st tx_queue "
> +               seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
>                            "rx_queue tr tm->when retrnsmt   uid  timeout "
>                            "inode ref pointer drops");
>         else {
>                 struct ping_iter_state *state = seq->private;
> -               int len;
>
> -               ping_v4_format_sock(v, seq, state->bucket, &len);
> -               seq_printf(seq, "%*s\n", 127 - len, "");
> +               ping_v4_format_sock(v, seq, state->bucket);
>         }
> +       seq_pad(seq, '\n');
>         return 0;
>  }
>
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index b14266b..2948b76 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -2598,13 +2598,13 @@ void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
>  EXPORT_SYMBOL(tcp_proc_unregister);
>
>  static void get_openreq4(const struct sock *sk, const struct request_sock *req,
> -                        struct seq_file *f, int i, kuid_t uid, int *len)
> +                        struct seq_file *f, int i, kuid_t uid)
>  {
>         const struct inet_request_sock *ireq = inet_rsk(req);
>         long delta = req->expires - jiffies;
>
>         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
> -               " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK%n",
> +               " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
>                 i,
>                 ireq->loc_addr,
>                 ntohs(inet_sk(sk)->inet_sport),
> @@ -2619,11 +2619,10 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
>                 0,  /* non standard timer */
>                 0, /* open_requests have no inode */
>                 atomic_read(&sk->sk_refcnt),
> -               req,
> -               len);
> +               req);
>  }
>
> -static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
> +static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
>  {
>         int timer_active;
>         unsigned long timer_expires;
> @@ -2662,7 +2661,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
>                 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
>
>         seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
> -                       "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d%n",
> +                       "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
>                 i, src, srcp, dest, destp, sk->sk_state,
>                 tp->write_seq - tp->snd_una,
>                 rx_queue,
> @@ -2679,12 +2678,11 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
>                 tp->snd_cwnd,
>                 sk->sk_state == TCP_LISTEN ?
>                     (fastopenq ? fastopenq->max_qlen : 0) :
> -                   (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh),
> -               len);
> +                   (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
>  }
>
>  static void get_timewait4_sock(const struct inet_timewait_sock *tw,
> -                              struct seq_file *f, int i, int *len)
> +                              struct seq_file *f, int i)
>  {
>         __be32 dest, src;
>         __u16 destp, srcp;
> @@ -2696,10 +2694,10 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
>         srcp  = ntohs(tw->tw_sport);
>
>         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
> -               " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
> +               " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
>                 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
>                 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
> -               atomic_read(&tw->tw_refcnt), tw, len);
> +               atomic_read(&tw->tw_refcnt), tw);
>  }
>
>  #define TMPSZ 150
> @@ -2707,11 +2705,10 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
>  static int tcp4_seq_show(struct seq_file *seq, void *v)
>  {
>         struct tcp_iter_state *st;
> -       int len;
>
> +       seq_setwidth(seq, TMPSZ - 1);
>         if (v == SEQ_START_TOKEN) {
> -               seq_printf(seq, "%-*s\n", TMPSZ - 1,
> -                          "  sl  local_address rem_address   st tx_queue "
> +               seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
>                            "rx_queue tr tm->when retrnsmt   uid  timeout "
>                            "inode");
>                 goto out;
> @@ -2721,17 +2718,17 @@ static int tcp4_seq_show(struct seq_file *seq, void *v)
>         switch (st->state) {
>         case TCP_SEQ_STATE_LISTENING:
>         case TCP_SEQ_STATE_ESTABLISHED:
> -               get_tcp4_sock(v, seq, st->num, &len);
> +               get_tcp4_sock(v, seq, st->num);
>                 break;
>         case TCP_SEQ_STATE_OPENREQ:
> -               get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
> +               get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid);
>                 break;
>         case TCP_SEQ_STATE_TIME_WAIT:
> -               get_timewait4_sock(v, seq, st->num, &len);
> +               get_timewait4_sock(v, seq, st->num);
>                 break;
>         }
> -       seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
>  out:
> +       seq_pad(seq, '\n');
>         return 0;
>  }
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 74d2c95..31c132c 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -2150,7 +2150,7 @@ EXPORT_SYMBOL(udp_proc_unregister);
>
>  /* ------------------------------------------------------------------------ */
>  static void udp4_format_sock(struct sock *sp, struct seq_file *f,
> -               int bucket, int *len)
> +               int bucket)
>  {
>         struct inet_sock *inet = inet_sk(sp);
>         __be32 dest = inet->inet_daddr;
> @@ -2159,7 +2159,7 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
>         __u16 srcp        = ntohs(inet->inet_sport);
>
>         seq_printf(f, "%5d: %08X:%04X %08X:%04X"
> -               " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
> +               " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
>                 bucket, src, srcp, dest, destp, sp->sk_state,
>                 sk_wmem_alloc_get(sp),
>                 sk_rmem_alloc_get(sp),
> @@ -2167,23 +2167,22 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
>                 from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
>                 0, sock_i_ino(sp),
>                 atomic_read(&sp->sk_refcnt), sp,
> -               atomic_read(&sp->sk_drops), len);
> +               atomic_read(&sp->sk_drops));
>  }
>
>  int udp4_seq_show(struct seq_file *seq, void *v)
>  {
> +       seq_setwidth(seq, 127);
>         if (v == SEQ_START_TOKEN)
> -               seq_printf(seq, "%-127s\n",
> -                          "  sl  local_address rem_address   st tx_queue "
> +               seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
>                            "rx_queue tr tm->when retrnsmt   uid  timeout "
>                            "inode ref pointer drops");
>         else {
>                 struct udp_iter_state *state = seq->private;
> -               int len;
>
> -               udp4_format_sock(v, seq, state->bucket, &len);
> -               seq_printf(seq, "%*s\n", 127 - len, "");
> +               udp4_format_sock(v, seq, state->bucket);
>         }
> +       seq_pad(seq, '\n');
>         return 0;
>  }
>
> diff --git a/net/phonet/socket.c b/net/phonet/socket.c
> index 77e38f7..008214a 100644
> --- a/net/phonet/socket.c
> +++ b/net/phonet/socket.c
> @@ -595,26 +595,25 @@ static void pn_sock_seq_stop(struct seq_file *seq, void *v)
>
>  static int pn_sock_seq_show(struct seq_file *seq, void *v)
>  {
> -       int len;
> -
> +       seq_setwidth(seq, 127);
>         if (v == SEQ_START_TOKEN)
> -               seq_printf(seq, "%s%n", "pt  loc  rem rs st tx_queue rx_queue "
> -                       "  uid inode ref pointer drops", &len);
> +               seq_puts(seq, "pt  loc  rem rs st tx_queue rx_queue "
> +                       "  uid inode ref pointer drops");
>         else {
>                 struct sock *sk = v;
>                 struct pn_sock *pn = pn_sk(sk);
>
>                 seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
> -                       "%d %pK %d%n",
> +                       "%d %pK %d",
>                         sk->sk_protocol, pn->sobject, pn->dobject,
>                         pn->resource, sk->sk_state,
>                         sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
>                         from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
>                         sock_i_ino(sk),
>                         atomic_read(&sk->sk_refcnt), sk,
> -                       atomic_read(&sk->sk_drops), &len);
> +                       atomic_read(&sk->sk_drops));
>         }
> -       seq_printf(seq, "%*s\n", 127 - len, "");
> +       seq_pad(seq, '\n');
>         return 0;
>  }
>
> @@ -785,20 +784,19 @@ static void pn_res_seq_stop(struct seq_file *seq, void *v)
>
>  static int pn_res_seq_show(struct seq_file *seq, void *v)
>  {
> -       int len;
> -
> +       seq_setwidth(seq, 63);
>         if (v == SEQ_START_TOKEN)
> -               seq_printf(seq, "%s%n", "rs   uid inode", &len);
> +               seq_puts(seq, "rs   uid inode");
>         else {
>                 struct sock **psk = v;
>                 struct sock *sk = *psk;
>
> -               seq_printf(seq, "%02X %5u %lu%n",
> +               seq_printf(seq, "%02X %5u %lu",
>                            (int) (psk - pnres.sk),
>                            from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
> -                          sock_i_ino(sk), &len);
> +                          sock_i_ino(sk));
>         }
> -       seq_printf(seq, "%*s\n", 63 - len, "");
> +       seq_pad(seq, '\n');
>         return 0;
>  }
>
> diff --git a/net/sctp/objcnt.c b/net/sctp/objcnt.c
> index 5ea573b..647396b 100644
> --- a/net/sctp/objcnt.c
> +++ b/net/sctp/objcnt.c
> @@ -79,12 +79,13 @@ static sctp_dbg_objcnt_entry_t sctp_dbg_objcnt[] = {
>   */
>  static int sctp_objcnt_seq_show(struct seq_file *seq, void *v)
>  {
> -       int i, len;
> +       int i;
>
>         i = (int)*(loff_t *)v;
> -       seq_printf(seq, "%s: %d%n", sctp_dbg_objcnt[i].label,
> -                               atomic_read(sctp_dbg_objcnt[i].counter), &len);
> -       seq_printf(seq, "%*s\n", 127 - len, "");
> +       seq_setwidth(seq, 127);
> +       seq_printf(seq, "%s: %d", sctp_dbg_objcnt[i].label,
> +                               atomic_read(sctp_dbg_objcnt[i].counter));
> +       seq_pad(seq, '\n');
>         return 0;
>  }
>
> --
> 1.7.1



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/2] remove all uses of printf's %n
  2013-09-23 21:24         ` Kees Cook
@ 2013-09-30  8:16           ` Tetsuo Handa
  0 siblings, 0 replies; 11+ messages in thread
From: Tetsuo Handa @ 2013-09-30  8:16 UTC (permalink / raw)
  To: akpm
  Cc: keescook, jslaby, viro, xemul, linux-kernel, netdev, linux-sctp,
	linux, dan.carpenter, geert, JBeulich, joe, kosaki.motohiro

Hello.

As it seems that there is no critical problem (naming preference can easily be
fixed if needed), can these patches go to linux-next?

If these patches are accepted, Kees Cook will submit a patch which removes %n
support from vsnprintf() ( https://lkml.org/lkml/2013/9/16/54 ).

Regards.
----------------------------------------
>From 02b28fd709971f71e5de9a5b595ff4fd059028b3 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Thu, 19 Sep 2013 17:23:17 +0900
Subject: [PATCH] seq_file: Introduce seq_setwidth() and seq_pad()

There are several users who want to know bytes written by seq_*() for alignment
purpose. Currently they are using %n format for knowing it because seq_*()
returns 0 on success.

This patch introduces seq_setwidth() and seq_pad() for allowing them to align
without using %n format.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
---
 fs/seq_file.c            |   15 +++++++++++++++
 include/linux/seq_file.h |   15 +++++++++++++++
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 3135c25..40e471e 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -764,6 +764,21 @@ int seq_write(struct seq_file *seq, const void *data, size_t len)
 }
 EXPORT_SYMBOL(seq_write);
 
+/**
+ * seq_pad - write padding spaces to buffer
+ * @m: seq_file identifying the buffer to which data should be written
+ * @c: the byte to append after padding if non-zero
+ */
+void seq_pad(struct seq_file *m, char c)
+{
+	int size = m->pad_until - m->count;
+	if (size > 0)
+		seq_printf(m, "%*s", size, "");
+	if (c)
+		seq_putc(m, c);
+}
+EXPORT_SYMBOL(seq_pad);
+
 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
 {
 	struct list_head *lh;
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 4e32edc..52e0097 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -20,6 +20,7 @@ struct seq_file {
 	size_t size;
 	size_t from;
 	size_t count;
+	size_t pad_until;
 	loff_t index;
 	loff_t read_pos;
 	u64 version;
@@ -79,6 +80,20 @@ static inline void seq_commit(struct seq_file *m, int num)
 	}
 }
 
+/**
+ * seq_setwidth - set padding width
+ * @m: the seq_file handle
+ * @size: the max number of bytes to pad.
+ *
+ * Call seq_setwidth() for setting max width, then call seq_printf() etc. and
+ * finally call seq_pad() to pad the remaining bytes.
+ */
+static inline void seq_setwidth(struct seq_file *m, size_t size)
+{
+	m->pad_until = m->count + size;
+}
+void seq_pad(struct seq_file *m, char c);
+
 char *mangle_path(char *s, const char *p, const char *esc);
 int seq_open(struct file *, const struct seq_operations *);
 ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);
-- 
1.7.1
----------------------------------------
>From f8b60ebe3971901b93dedb8eee0f85b60d0fdc5f Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Fri, 20 Sep 2013 12:01:07 +0900
Subject: [PATCH] Remove "%n" usage from seq_file users.

All seq_printf() users are using "%n" for calculating padding size, convert
them to use seq_setwidth() / seq_pad() pair.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
---
 fs/proc/consoles.c   |   10 ++++------
 fs/proc/nommu.c      |   12 +++++-------
 fs/proc/task_mmu.c   |   20 ++++++--------------
 fs/proc/task_nommu.c |   19 ++++++-------------
 net/ipv4/fib_trie.c  |   13 +++++++------
 net/ipv4/ping.c      |   15 +++++++--------
 net/ipv4/tcp_ipv4.c  |   33 +++++++++++++++------------------
 net/ipv4/udp.c       |   15 +++++++--------
 net/phonet/socket.c  |   24 +++++++++++-------------
 net/sctp/objcnt.c    |    9 +++++----
 10 files changed, 73 insertions(+), 97 deletions(-)

diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index b701eaa..51942d5 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -29,7 +29,6 @@ static int show_console_dev(struct seq_file *m, void *v)
 	char flags[ARRAY_SIZE(con_flags) + 1];
 	struct console *con = v;
 	unsigned int a;
-	int len;
 	dev_t dev = 0;
 
 	if (con->device) {
@@ -47,11 +46,10 @@ static int show_console_dev(struct seq_file *m, void *v)
 			con_flags[a].name : ' ';
 	flags[a] = 0;
 
-	seq_printf(m, "%s%d%n", con->name, con->index, &len);
-	len = 21 - len;
-	if (len < 1)
-		len = 1;
-	seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
+	seq_setwidth(m, 21 - 1);
+	seq_printf(m, "%s%d", con->name, con->index);
+	seq_pad(m, ' ');
+	seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',
 			con->write ? 'W' : '-', con->unblank ? 'U' : '-',
 			flags);
 	if (dev)
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index ccfd99b..5f9bc8a 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -39,7 +39,7 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 	unsigned long ino = 0;
 	struct file *file;
 	dev_t dev = 0;
-	int flags, len;
+	int flags;
 
 	flags = region->vm_flags;
 	file = region->vm_file;
@@ -50,8 +50,9 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 		ino = inode->i_ino;
 	}
 
+	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
 	seq_printf(m,
-		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 		   region->vm_start,
 		   region->vm_end,
 		   flags & VM_READ ? 'r' : '-',
@@ -59,13 +60,10 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 		   flags & VM_EXEC ? 'x' : '-',
 		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
 		   ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
-		   MAJOR(dev), MINOR(dev), ino, &len);
+		   MAJOR(dev), MINOR(dev), ino);
 
 	if (file) {
-		len = 25 + sizeof(void *) * 6 - len;
-		if (len < 1)
-			len = 1;
-		seq_printf(m, "%*c", len, ' ');
+		seq_pad(m, ' ');
 		seq_path(m, &file->f_path, "");
 	}
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 7366e9d..cc24165 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -83,14 +83,6 @@ unsigned long task_statm(struct mm_struct *mm,
 	return mm->total_vm;
 }
 
-static void pad_len_spaces(struct seq_file *m, int len)
-{
-	len = 25 + sizeof(void*) * 6 - len;
-	if (len < 1)
-		len = 1;
-	seq_printf(m, "%*c", len, ' ');
-}
-
 #ifdef CONFIG_NUMA
 /*
  * These functions are for numa_maps but called in generic **maps seq_file
@@ -268,7 +260,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 	unsigned long long pgoff = 0;
 	unsigned long start, end;
 	dev_t dev = 0;
-	int len;
 	const char *name = NULL;
 
 	if (file) {
@@ -286,7 +277,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 	if (stack_guard_page_end(vma, end))
 		end -= PAGE_SIZE;
 
-	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
+	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 			start,
 			end,
 			flags & VM_READ ? 'r' : '-',
@@ -294,14 +286,14 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 			flags & VM_EXEC ? 'x' : '-',
 			flags & VM_MAYSHARE ? 's' : 'p',
 			pgoff,
-			MAJOR(dev), MINOR(dev), ino, &len);
+			MAJOR(dev), MINOR(dev), ino);
 
 	/*
 	 * Print the dentry name for named mappings, and a
 	 * special [heap] marker for the heap:
 	 */
 	if (file) {
-		pad_len_spaces(m, len);
+		seq_pad(m, ' ');
 		seq_path(m, &file->f_path, "\n");
 		goto done;
 	}
@@ -333,7 +325,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 				name = "[stack]";
 			} else {
 				/* Thread stack in /proc/PID/maps */
-				pad_len_spaces(m, len);
+				seq_pad(m, ' ');
 				seq_printf(m, "[stack:%d]", tid);
 			}
 		}
@@ -341,7 +333,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 
 done:
 	if (name) {
-		pad_len_spaces(m, len);
+		seq_pad(m, ' ');
 		seq_puts(m, name);
 	}
 	seq_putc(m, '\n');
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 56123a6..678455d 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -123,14 +123,6 @@ unsigned long task_statm(struct mm_struct *mm,
 	return size;
 }
 
-static void pad_len_spaces(struct seq_file *m, int len)
-{
-	len = 25 + sizeof(void*) * 6 - len;
-	if (len < 1)
-		len = 1;
-	seq_printf(m, "%*c", len, ' ');
-}
-
 /*
  * display a single VMA to a sequenced file
  */
@@ -142,7 +134,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 	unsigned long ino = 0;
 	struct file *file;
 	dev_t dev = 0;
-	int flags, len;
+	int flags;
 	unsigned long long pgoff = 0;
 
 	flags = vma->vm_flags;
@@ -155,8 +147,9 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 		pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
 	}
 
+	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
 	seq_printf(m,
-		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 		   vma->vm_start,
 		   vma->vm_end,
 		   flags & VM_READ ? 'r' : '-',
@@ -164,16 +157,16 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 		   flags & VM_EXEC ? 'x' : '-',
 		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
 		   pgoff,
-		   MAJOR(dev), MINOR(dev), ino, &len);
+		   MAJOR(dev), MINOR(dev), ino);
 
 	if (file) {
-		pad_len_spaces(m, len);
+		seq_pad(m, ' ');
 		seq_path(m, &file->f_path, "");
 	} else if (mm) {
 		pid_t tid = vm_is_stack(priv->task, vma, is_pid);
 
 		if (tid != 0) {
-			pad_len_spaces(m, len);
+			seq_pad(m, ' ');
 			/*
 			 * Thread stack in /proc/PID/task/TID/maps or
 			 * the main process stack.
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 3df6d3e..b1af50e 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2530,16 +2530,17 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
 		list_for_each_entry_rcu(fa, &li->falh, fa_list) {
 			const struct fib_info *fi = fa->fa_info;
 			unsigned int flags = fib_flag_trans(fa->fa_type, mask, fi);
-			int len;
 
 			if (fa->fa_type == RTN_BROADCAST
 			    || fa->fa_type == RTN_MULTICAST)
 				continue;
 
+			seq_setwidth(seq, 127);
+
 			if (fi)
 				seq_printf(seq,
 					 "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
-					 "%d\t%08X\t%d\t%u\t%u%n",
+					 "%d\t%08X\t%d\t%u\t%u",
 					 fi->fib_dev ? fi->fib_dev->name : "*",
 					 prefix,
 					 fi->fib_nh->nh_gw, flags, 0, 0,
@@ -2548,15 +2549,15 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
 					 (fi->fib_advmss ?
 					  fi->fib_advmss + 40 : 0),
 					 fi->fib_window,
-					 fi->fib_rtt >> 3, &len);
+					 fi->fib_rtt >> 3);
 			else
 				seq_printf(seq,
 					 "*\t%08X\t%08X\t%04X\t%d\t%u\t"
-					 "%d\t%08X\t%d\t%u\t%u%n",
+					 "%d\t%08X\t%d\t%u\t%u",
 					 prefix, 0, flags, 0, 0, 0,
-					 mask, 0, 0, 0, &len);
+					 mask, 0, 0, 0);
 
-			seq_printf(seq, "%*s\n", 127 - len, "");
+			seq_pad(seq, '\n');
 		}
 	}
 
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index d7d9882..94cc685 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -1073,7 +1073,7 @@ void ping_seq_stop(struct seq_file *seq, void *v)
 EXPORT_SYMBOL_GPL(ping_seq_stop);
 
 static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
-		int bucket, int *len)
+		int bucket)
 {
 	struct inet_sock *inet = inet_sk(sp);
 	__be32 dest = inet->inet_daddr;
@@ -1082,7 +1082,7 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
 	__u16 srcp = ntohs(inet->inet_sport);
 
 	seq_printf(f, "%5d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
@@ -1090,23 +1090,22 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp,
-		atomic_read(&sp->sk_drops), len);
+		atomic_read(&sp->sk_drops));
 }
 
 static int ping_v4_seq_show(struct seq_file *seq, void *v)
 {
+	seq_setwidth(seq, 127);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%-127s\n",
-			   "  sl  local_address rem_address   st tx_queue "
+		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
 			   "rx_queue tr tm->when retrnsmt   uid  timeout "
 			   "inode ref pointer drops");
 	else {
 		struct ping_iter_state *state = seq->private;
-		int len;
 
-		ping_v4_format_sock(v, seq, state->bucket, &len);
-		seq_printf(seq, "%*s\n", 127 - len, "");
+		ping_v4_format_sock(v, seq, state->bucket);
 	}
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b14266b..2948b76 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2598,13 +2598,13 @@ void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
 EXPORT_SYMBOL(tcp_proc_unregister);
 
 static void get_openreq4(const struct sock *sk, const struct request_sock *req,
-			 struct seq_file *f, int i, kuid_t uid, int *len)
+			 struct seq_file *f, int i, kuid_t uid)
 {
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	long delta = req->expires - jiffies;
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
 		i,
 		ireq->loc_addr,
 		ntohs(inet_sk(sk)->inet_sport),
@@ -2619,11 +2619,10 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
 		0,  /* non standard timer */
 		0, /* open_requests have no inode */
 		atomic_read(&sk->sk_refcnt),
-		req,
-		len);
+		req);
 }
 
-static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
+static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
 {
 	int timer_active;
 	unsigned long timer_expires;
@@ -2662,7 +2661,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
-			"%08X %5u %8d %lu %d %pK %lu %lu %u %u %d%n",
+			"%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
 		i, src, srcp, dest, destp, sk->sk_state,
 		tp->write_seq - tp->snd_una,
 		rx_queue,
@@ -2679,12 +2678,11 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		tp->snd_cwnd,
 		sk->sk_state == TCP_LISTEN ?
 		    (fastopenq ? fastopenq->max_qlen : 0) :
-		    (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh),
-		len);
+		    (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
 }
 
 static void get_timewait4_sock(const struct inet_timewait_sock *tw,
-			       struct seq_file *f, int i, int *len)
+			       struct seq_file *f, int i)
 {
 	__be32 dest, src;
 	__u16 destp, srcp;
@@ -2696,10 +2694,10 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 	srcp  = ntohs(tw->tw_sport);
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
 		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
 		3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
-		atomic_read(&tw->tw_refcnt), tw, len);
+		atomic_read(&tw->tw_refcnt), tw);
 }
 
 #define TMPSZ 150
@@ -2707,11 +2705,10 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 static int tcp4_seq_show(struct seq_file *seq, void *v)
 {
 	struct tcp_iter_state *st;
-	int len;
 
+	seq_setwidth(seq, TMPSZ - 1);
 	if (v == SEQ_START_TOKEN) {
-		seq_printf(seq, "%-*s\n", TMPSZ - 1,
-			   "  sl  local_address rem_address   st tx_queue "
+		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
 			   "rx_queue tr tm->when retrnsmt   uid  timeout "
 			   "inode");
 		goto out;
@@ -2721,17 +2718,17 @@ static int tcp4_seq_show(struct seq_file *seq, void *v)
 	switch (st->state) {
 	case TCP_SEQ_STATE_LISTENING:
 	case TCP_SEQ_STATE_ESTABLISHED:
-		get_tcp4_sock(v, seq, st->num, &len);
+		get_tcp4_sock(v, seq, st->num);
 		break;
 	case TCP_SEQ_STATE_OPENREQ:
-		get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
+		get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid);
 		break;
 	case TCP_SEQ_STATE_TIME_WAIT:
-		get_timewait4_sock(v, seq, st->num, &len);
+		get_timewait4_sock(v, seq, st->num);
 		break;
 	}
-	seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
 out:
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 74d2c95..31c132c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2150,7 +2150,7 @@ EXPORT_SYMBOL(udp_proc_unregister);
 
 /* ------------------------------------------------------------------------ */
 static void udp4_format_sock(struct sock *sp, struct seq_file *f,
-		int bucket, int *len)
+		int bucket)
 {
 	struct inet_sock *inet = inet_sk(sp);
 	__be32 dest = inet->inet_daddr;
@@ -2159,7 +2159,7 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 	__u16 srcp	  = ntohs(inet->inet_sport);
 
 	seq_printf(f, "%5d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
@@ -2167,23 +2167,22 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp,
-		atomic_read(&sp->sk_drops), len);
+		atomic_read(&sp->sk_drops));
 }
 
 int udp4_seq_show(struct seq_file *seq, void *v)
 {
+	seq_setwidth(seq, 127);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%-127s\n",
-			   "  sl  local_address rem_address   st tx_queue "
+		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
 			   "rx_queue tr tm->when retrnsmt   uid  timeout "
 			   "inode ref pointer drops");
 	else {
 		struct udp_iter_state *state = seq->private;
-		int len;
 
-		udp4_format_sock(v, seq, state->bucket, &len);
-		seq_printf(seq, "%*s\n", 127 - len, "");
+		udp4_format_sock(v, seq, state->bucket);
 	}
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index 77e38f7..008214a 100644
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -595,26 +595,25 @@ static void pn_sock_seq_stop(struct seq_file *seq, void *v)
 
 static int pn_sock_seq_show(struct seq_file *seq, void *v)
 {
-	int len;
-
+	seq_setwidth(seq, 127);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%s%n", "pt  loc  rem rs st tx_queue rx_queue "
-			"  uid inode ref pointer drops", &len);
+		seq_puts(seq, "pt  loc  rem rs st tx_queue rx_queue "
+			"  uid inode ref pointer drops");
 	else {
 		struct sock *sk = v;
 		struct pn_sock *pn = pn_sk(sk);
 
 		seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
-			"%d %pK %d%n",
+			"%d %pK %d",
 			sk->sk_protocol, pn->sobject, pn->dobject,
 			pn->resource, sk->sk_state,
 			sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
 			from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
 			sock_i_ino(sk),
 			atomic_read(&sk->sk_refcnt), sk,
-			atomic_read(&sk->sk_drops), &len);
+			atomic_read(&sk->sk_drops));
 	}
-	seq_printf(seq, "%*s\n", 127 - len, "");
+	seq_pad(seq, '\n');
 	return 0;
 }
 
@@ -785,20 +784,19 @@ static void pn_res_seq_stop(struct seq_file *seq, void *v)
 
 static int pn_res_seq_show(struct seq_file *seq, void *v)
 {
-	int len;
-
+	seq_setwidth(seq, 63);
 	if (v == SEQ_START_TOKEN)
-		seq_printf(seq, "%s%n", "rs   uid inode", &len);
+		seq_puts(seq, "rs   uid inode");
 	else {
 		struct sock **psk = v;
 		struct sock *sk = *psk;
 
-		seq_printf(seq, "%02X %5u %lu%n",
+		seq_printf(seq, "%02X %5u %lu",
 			   (int) (psk - pnres.sk),
 			   from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
-			   sock_i_ino(sk), &len);
+			   sock_i_ino(sk));
 	}
-	seq_printf(seq, "%*s\n", 63 - len, "");
+	seq_pad(seq, '\n');
 	return 0;
 }
 
diff --git a/net/sctp/objcnt.c b/net/sctp/objcnt.c
index 5ea573b..647396b 100644
--- a/net/sctp/objcnt.c
+++ b/net/sctp/objcnt.c
@@ -79,12 +79,13 @@ static sctp_dbg_objcnt_entry_t sctp_dbg_objcnt[] = {
  */
 static int sctp_objcnt_seq_show(struct seq_file *seq, void *v)
 {
-	int i, len;
+	int i;
 
 	i = (int)*(loff_t *)v;
-	seq_printf(seq, "%s: %d%n", sctp_dbg_objcnt[i].label,
-				atomic_read(sctp_dbg_objcnt[i].counter), &len);
-	seq_printf(seq, "%*s\n", 127 - len, "");
+	seq_setwidth(seq, 127);
+	seq_printf(seq, "%s: %d", sctp_dbg_objcnt[i].label,
+				atomic_read(sctp_dbg_objcnt[i].counter));
+	seq_pad(seq, '\n');
 	return 0;
 }
 
-- 
1.7.1

^ permalink raw reply related	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2013-09-30  8:16 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz follow: Atom feed
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2013-09-20  4:09       ` [PATCH 1/2] remove all uses of printf's %n Tetsuo Handa
2013-09-20  4:23         ` Joe Perches
2013-09-20  4:53           ` Kees Cook
2013-09-20  8:08         ` Jiri Slaby
2013-09-20 19:24           ` Kees Cook
2013-09-20 19:33             ` Joe Perches
2013-09-21  0:28             ` Tetsuo Handa
2013-09-22  8:09               ` George Spelvin
2013-09-22  8:16               ` Geert Uytterhoeven
2013-09-23 21:24         ` Kees Cook
2013-09-30  8:16           ` Tetsuo Handa

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