[PATCH 1/7] pipe, sysctl: drop 'min' parameter from pipe-max-size converter

Eric Biggers
2018-01-08T05:40:37Z

From: Eric Biggers <ebiggers@google.com>

Before validating the given value against pipe_min_size,
do_proc_dopipe_max_size_conv() calls round_pipe_size(), which rounds the
value up to pipe_min_size. Therefore, the second check against
pipe_min_size is redundant. Remove it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/pipe.c | 10 +++-------
include/linux/pipe_fs_i.h | 2 +-
kernel/sysctl.c | 15 +--------------
3 files changed, 5 insertions(+), 22 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 6d98566201ef..a75f5d2ca99c 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -35,11 +35,6 @@
*/
unsigned int pipe_max_size = 1048576;

-/*
- * Minimum pipe size, as required by POSIX
- */
-unsigned int pipe_min_size = PAGE_SIZE;
-
/* Maximum allocatable pages per user. Hard limit is unset by default, soft
* matches default values.
*/
@@ -1024,8 +1019,9 @@ unsigned int round_pipe_size(unsigned int size)
{
unsigned long nr_pages;

- if (size < pipe_min_size)
- size = pipe_min_size;
+ /* Minimum pipe size, as required by POSIX */
+ if (size < PAGE_SIZE)
+ size = PAGE_SIZE;

nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (nr_pages == 0)
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 2dc5e9870fcd..7d9beda14584 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -167,7 +167,7 @@ void pipe_lock(struct pipe_inode_info *);
void pipe_unlock(struct pipe_inode_info *);
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);

-extern unsigned int pipe_max_size, pipe_min_size;
+extern unsigned int pipe_max_size;
extern unsigned long pipe_user_pages_hard;
extern unsigned long pipe_user_pages_soft;
int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 557d46728577..a71ebb5c5182 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1820,7 +1820,6 @@ static struct ctl_table fs_table[] = {
.maxlen = sizeof(pipe_max_size),
.mode = 0644,
.proc_handler = &pipe_proc_fn,
- .extra1 = &pipe_min_size,
},
{
.procname = "pipe-user-pages-hard",
@@ -2622,16 +2621,10 @@ int proc_douintvec_minmax(struct ctl_table *table, int write,
do_proc_douintvec_minmax_conv, &param);
}

-struct do_proc_dopipe_max_size_conv_param {
- unsigned int *min;
-};
-
static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
unsigned int *valp,
int write, void *data)
{
- struct do_proc_dopipe_max_size_conv_param *param = data;
-
if (write) {
unsigned int val;

@@ -2642,9 +2635,6 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
if (val == 0)
return -EINVAL;

- if (param->min && *param->min > val)
- return -ERANGE;
-
*valp = val;
} else {
unsigned int val = *valp;
@@ -2657,11 +2647,8 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
int proc_dopipe_max_size(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
- struct do_proc_dopipe_max_size_conv_param param = {
- .min = (unsigned int *) table->extra1,
- };
return do_proc_douintvec(table, write, buffer, lenp, ppos,
- do_proc_dopipe_max_size_conv, &param);
+ do_proc_dopipe_max_size_conv, NULL);
}

static void validate_coredump_safety(void)
--
2.15.1