[PATCH 0/2] sctp: socket cleanups

[PATCH 0/2] sctp: socket cleanups

[Joe Perches]

Size trivially reduced as well.

$ size net/sctp/socket.o
   text	   data	    bss	    dec	    hex	filename
  55720	    442	  14988	  71150	  115ee	net/sctp/socket.o.new
  55730	    442	  14996	  71168	  11600	net/sctp/socket.o.old

Joe Perches (2):
  sctp: sctp_sendmsg: Don't initialize default_sinfo
  sctp: sctp_sendmsg: Don't test known non-null sinfo

 net/sctp/socket.c |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

-- 
1.7.5.rc3.dirty

[PATCH 1/2] sctp: sctp_sendmsg: Don't initialize default_sinfo

[Joe Perches]

This variable only needs initialization when cmsgs.info
is NULL.

Don't use memset, just initialize every struct member.

Signed-off-by: Joe Perches <joe@perches.com>
---
 net/sctp/socket.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 33d9ee6..a5d3560 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1496,8 +1496,8 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 	struct sctp_chunk *chunk;
 	union sctp_addr to;
 	struct sockaddr *msg_name = NULL;
-	struct sctp_sndrcvinfo default_sinfo = { 0 };
 	struct sctp_sndrcvinfo *sinfo;
+	struct sctp_sndrcvinfo default_sinfo;
 	struct sctp_initmsg *sinit;
 	sctp_assoc_t associd = 0;
 	sctp_cmsgs_t cmsgs = { NULL };
@@ -1761,10 +1761,13 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 		 * some defaults.
 		 */
 		default_sinfo.sinfo_stream = asoc->default_stream;
+		default_sinfo.sinfo_ssn = 0;
 		default_sinfo.sinfo_flags = asoc->default_flags;
 		default_sinfo.sinfo_ppid = asoc->default_ppid;
 		default_sinfo.sinfo_context = asoc->default_context;
 		default_sinfo.sinfo_timetolive = asoc->default_timetolive;
+		default_sinfo.sinfo_tsn = 0;
+		default_sinfo.sinfo_cumtsn = 0;
 		default_sinfo.sinfo_assoc_id = sctp_assoc2id(asoc);
 		sinfo = &default_sinfo;
 	}
-- 
1.7.5.rc3.dirty

[PATCH 2/2] sctp: sctp_sendmsg: Don't test known non-null sinfo

[Joe Perches]

It's already known non-null above.

Signed-off-by: Joe Perches <joe@perches.com>
---
 net/sctp/socket.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index a5d3560..10ebcd7 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1793,12 +1793,10 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 		goto out_free;
 	}
 
-	if (sinfo) {
-		/* Check for invalid stream. */
-		if (sinfo->sinfo_stream >= asoc->c.sinit_num_ostreams) {
-			err = -EINVAL;
-			goto out_free;
-		}
+	/* Check for invalid stream. */
+	if (sinfo->sinfo_stream >= asoc->c.sinit_num_ostreams) {
+		err = -EINVAL;
+		goto out_free;
 	}
 
 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
-- 
1.7.5.rc3.dirty

Re: [PATCH 1/2] sctp: sctp_sendmsg: Don't initialize default_sinfo

[David Miller]

From: Joe Perches <joe@perches.com>
Date: Thu, 12 May 2011 12:19:09 -0700

> This variable only needs initialization when cmsgs.info
> is NULL.
> 
> Don't use memset, just initialize every struct member.
> 
> Signed-off-by: Joe Perches <joe@perches.com>

I don't think you do this, this structure has padding holes on pretty
much every architecture.

It starts with 3 u16's, then there is a u32, so there is a 2-byte
piece of padding after the 3rd u16.

Can you prove that these uninitialized portions never make it to
userspace?  If you can, that proof belongs in the commit message.

I think it's too risky.

[PATCH 1/2 v2] sctp: sctp_sendmsg: Don't initialize default_sinfo

[Joe Perches]

This variable only needs initialization when cmsgs.info
is NULL.

Use memset to ensure padding is also zeroed so
kernel doesn't leak any data.

Signed-off-by: Joe Perches <joe@perches.com>

---

On Thu, 2011-05-12 at 17:06 -0400, David Miller wrote:
From: Joe Perches <joe@perches.com>
> Date: Thu, 12 May 2011 12:19:09 -0700
> > This variable only needs initialization when cmsgs.info
> > is NULL.
> > Don't use memset, just initialize every struct member.
> > Signed-off-by: Joe Perches <joe@perches.com>
> I don't think you do this, this structure has padding holes on pretty
> much every architecture.
> It starts with 3 u16's, then there is a u32, so there is a 2-byte
> piece of padding after the 3rd u16.
> Can you prove that these uninitialized portions never make it to
> userspace?  If you can, that proof belongs in the commit message.

Thanks David.  I didn't notice it went to userspace.

> I think it's too risky.

It is.  I like memset.

The current initialization isn't guaranteed by c90 standard
to zero all padding either.  In practice it does though.

The idea was to avoid doing a (non-memset) struct foo bar = {}
when unnecessary for every packet as it's only needed when
cmsgs.info is NULL.

 net/sctp/socket.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 33d9ee6..d4b8db1 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1496,7 +1496,7 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 	struct sctp_chunk *chunk;
 	union sctp_addr to;
 	struct sockaddr *msg_name = NULL;
-	struct sctp_sndrcvinfo default_sinfo = { 0 };
+	struct sctp_sndrcvinfo default_sinfo;
 	struct sctp_sndrcvinfo *sinfo;
 	struct sctp_initmsg *sinit;
 	sctp_assoc_t associd = 0;
@@ -1760,6 +1760,7 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 		/* If the user didn't specify SNDRCVINFO, make up one with
 		 * some defaults.
 		 */
+		memset(&default_sinfo, 0, sizeof(default_sinfo));
 		default_sinfo.sinfo_stream = asoc->default_stream;
 		default_sinfo.sinfo_flags = asoc->default_flags;
 		default_sinfo.sinfo_ppid = asoc->default_ppid;

Re: [PATCH 1/2 v2] sctp: sctp_sendmsg: Don't initialize default_sinfo

[David Miller]

From: Joe Perches <joe@perches.com>
Date: Thu, 12 May 2011 14:27:20 -0700

> This variable only needs initialization when cmsgs.info
> is NULL.
> 
> Use memset to ensure padding is also zeroed so
> kernel doesn't leak any data.
> 
> Signed-off-by: Joe Perches <joe@perches.com>

This looks a lot better, applied.

Re: [PATCH 2/2] sctp: sctp_sendmsg: Don't test known non-null sinfo

[David Miller]

From: Joe Perches <joe@perches.com>
Date: Thu, 12 May 2011 12:19:10 -0700

> It's already known non-null above.
> 
> Signed-off-by: Joe Perches <joe@perches.com>

Applied.