[linux] 03/07: sctp: avoid BUG_ON on sctp_wait_for_sndbuf (CVE-2017-5986)

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benh pushed a commit to branch wheezy-security
in repository linux.

commit 952f97d47ad1af8568bd4145fb59f7ab54d4a6e5
Author: Ben Hutchings <ben at decadent.org.uk>
Date:   Tue Mar 7 02:13:26 2017 +0000

    sctp: avoid BUG_ON on sctp_wait_for_sndbuf (CVE-2017-5986)
---
 debian/changelog                                   |  1 +
 ...sctp-avoid-bug_on-on-sctp_wait_for_sndbuf.patch | 37 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 39 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index d958796..e3c2274 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -78,6 +78,7 @@ linux (3.2.86-1) UNRELEASED; urgency=medium
 
   [ Ben Hutchings ]
   * ipc/shm: Fix shmat mmap nil-page protection (CVE-2017-5669)
+  * sctp: avoid BUG_ON on sctp_wait_for_sndbuf (CVE-2017-5986)
 
  -- Ben Hutchings <ben at decadent.org.uk>  Tue, 07 Mar 2017 01:47:48 +0000
 
diff --git a/debian/patches/bugfix/all/sctp-avoid-bug_on-on-sctp_wait_for_sndbuf.patch b/debian/patches/bugfix/all/sctp-avoid-bug_on-on-sctp_wait_for_sndbuf.patch
new file mode 100644
index 0000000..5569aa5
--- /dev/null
+++ b/debian/patches/bugfix/all/sctp-avoid-bug_on-on-sctp_wait_for_sndbuf.patch
@@ -0,0 +1,37 @@
+From: Marcelo Ricardo Leitner <marcelo.leitner at gmail.com>
+Date: Mon, 6 Feb 2017 18:10:31 -0200
+Subject: sctp: avoid BUG_ON on sctp_wait_for_sndbuf
+Origin: https://git.kernel.org/linus/2dcab598484185dea7ec22219c76dcdd59e3cb90
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-5986
+
+Alexander Popov reported that an application may trigger a BUG_ON in
+sctp_wait_for_sndbuf if the socket tx buffer is full, a thread is
+waiting on it to queue more data and meanwhile another thread peels off
+the association being used by the first thread.
+
+This patch replaces the BUG_ON call with a proper error handling. It
+will return -EPIPE to the original sendmsg call, similarly to what would
+have been done if the association wasn't found in the first place.
+
+Acked-by: Alexander Popov <alex.popov at linux.com>
+Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner at gmail.com>
+Reviewed-by: Xin Long <lucien.xin at gmail.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+[bwh: Backported to 3.2: adjust context]
+Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
+---
+ net/sctp/socket.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/net/sctp/socket.c
++++ b/net/sctp/socket.c
+@@ -6480,7 +6480,8 @@ static int sctp_wait_for_sndbuf(struct s
+ 		 */
+ 		sctp_release_sock(sk);
+ 		current_timeo = schedule_timeout(current_timeo);
+-		BUG_ON(sk != asoc->base.sk);
++		if (sk != asoc->base.sk)
++			goto do_error;
+ 		sctp_lock_sock(sk);
+ 
+ 		*timeo_p = current_timeo;
diff --git a/debian/patches/series b/debian/patches/series
index f74465e..b5d3004 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1107,6 +1107,7 @@ bugfix/all/netfilter-ipset-Check-and-reject-crazy-0-input-param.patch
 bugfix/all/KEYS-Don-t-permit-request_key-to-construct-a-new-key.patch
 bugfix/all/ecryptfs-fix-handling-of-directory-opening.patch
 bugfix/all/ipc-shm-fix-shmat-mmap-nil-page-protection.patch
+bugfix/all/sctp-avoid-bug_on-on-sctp_wait_for_sndbuf.patch
 
 # ABI maintenance
 debian/perf-hide-abi-change-in-3.2.30.patch

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