[ 3.5.y.z extended stable ] Patch "sctp: fix -ENOMEM result with invalid user space pointer in" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    sctp: fix -ENOMEM result with invalid user space pointer in

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 40ae9140264f5881e4aea548df436d4da09480df Mon Sep 17 00:00:00 2001
From: Tommi Rantala <tt.rantala at gmail.com>
Date: Thu, 22 Nov 2012 03:23:16 +0000
Subject: [PATCH] sctp: fix -ENOMEM result with invalid user space pointer in
 sendto() syscall

commit 6e51fe7572590d8d86e93b547fab6693d305fd0d upstream.

Consider the following program, that sets the second argument to the
sendto() syscall incorrectly:

 #include <string.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>

 int main(void)
 {
         int fd;
         struct sockaddr_in sa;

         fd = socket(AF_INET, SOCK_STREAM, 132 /*IPPROTO_SCTP*/);
         if (fd < 0)
                 return 1;

         memset(&sa, 0, sizeof(sa));
         sa.sin_family = AF_INET;
         sa.sin_addr.s_addr = inet_addr("127.0.0.1");
         sa.sin_port = htons(11111);

         sendto(fd, NULL, 1, 0, (struct sockaddr *)&sa, sizeof(sa));

         return 0;
 }

We get -ENOMEM:

 $ strace -e sendto ./demo
 sendto(3, NULL, 1, 0, {sa_family=AF_INET, sin_port=htons(11111), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 ENOMEM (Cannot allocate memory)

Propagate the error code from sctp_user_addto_chunk(), so that we will
tell user space what actually went wrong:

 $ strace -e sendto ./demo
 sendto(3, NULL, 1, 0, {sa_family=AF_INET, sin_port=htons(11111), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EFAULT (Bad address)

Noticed while running Trinity (the syscall fuzzer).

Signed-off-by: Tommi Rantala <tt.rantala at gmail.com>
Acked-by: Vlad Yasevich <vyasevich at gmail.com>
Acked-by: Neil Horman <nhorman at tuxdriver.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 net/sctp/chunk.c  |   13 +++++++++----
 net/sctp/socket.c |    4 ++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
index 9534bf9..0018b65 100644
--- a/net/sctp/chunk.c
+++ b/net/sctp/chunk.c
@@ -183,7 +183,7 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,

 	msg = sctp_datamsg_new(GFP_KERNEL);
 	if (!msg)
-		return NULL;
+		return ERR_PTR(-ENOMEM);

 	/* Note: Calculate this outside of the loop, so that all fragments
 	 * have the same expiration.
@@ -280,8 +280,11 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,

 		chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);

-		if (!chunk)
+		if (!chunk) {
+			err = -ENOMEM;
 			goto errout;
+		}
+
 		err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 		if (err < 0)
 			goto errout_chunk_free;
@@ -315,8 +318,10 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,

 		chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);

-		if (!chunk)
+		if (!chunk) {
+			err = -ENOMEM;
 			goto errout;
+		}

 		err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);

@@ -342,7 +347,7 @@ errout:
 		sctp_chunk_free(chunk);
 	}
 	sctp_datamsg_put(msg);
-	return NULL;
+	return ERR_PTR(err);
 }

 /* Check whether this message has expired. */
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 31c7bfc..944cfce 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1908,8 +1908,8 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,

 	/* Break the message into multiple chunks of maximum size. */
 	datamsg = sctp_datamsg_from_user(asoc, sinfo, msg, msg_len);
-	if (!datamsg) {
-		err = -ENOMEM;
+	if (IS_ERR(datamsg)) {
+		err = PTR_ERR(datamsg);
 		goto out_free;
 	}

--
1.7.9.5