[linux] 01/02: sctp: avoid BUG_ON on sctp_wait_for_sndbuf (CVE-2017-5986)

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carnil pushed a commit to branch jessie-security
in repository linux.

commit 4c00f8e156355691a6a7a8e982b6668da39cb77f
Author: Salvatore Bonaccorso <carnil at debian.org>
Date:   Mon Feb 20 17:58:49 2017 +0100

    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 | 40 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 42 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index fa82d46..d614514 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,6 +1,7 @@
 linux (3.16.39-1+deb8u2) UNRELEASED; urgency=medium
 
   * ipc/shm: Fix shmat mmap nil-page protection (CVE-2017-5669)
+  * sctp: avoid BUG_ON on sctp_wait_for_sndbuf (CVE-2017-5986)
 
  -- Salvatore Bonaccorso <carnil at debian.org>  Tue, 07 Mar 2017 17:10:30 +0100
 
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..fb411c8
--- /dev/null
+++ b/debian/patches/bugfix/all/sctp-avoid-BUG_ON-on-sctp_wait_for_sndbuf.patch
@@ -0,0 +1,40 @@
+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>
+---
+ net/sctp/socket.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/net/sctp/socket.c b/net/sctp/socket.c
+index 37eeab7..e214d2e 100644
+--- a/net/sctp/socket.c
++++ b/net/sctp/socket.c
+@@ -7426,7 +7426,8 @@ static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
+ 		 */
+ 		release_sock(sk);
+ 		current_timeo = schedule_timeout(current_timeo);
+-		BUG_ON(sk != asoc->base.sk);
++		if (sk != asoc->base.sk)
++			goto do_error;
+ 		lock_sock(sk);
+ 
+ 		*timeo_p = current_timeo;
+-- 
+2.1.4
+
diff --git a/debian/patches/series b/debian/patches/series
index ccac829..735a523 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -694,6 +694,7 @@ bugfix/all/ip6_gre-fix-ip6gre_err-invalid-reads.patch
 bugfix/x86/kvm-fix-page-struct-leak-in-handle_vmon.patch
 bugfix/all/ipv4-keep-skb-dst-around-in-presence-of-ip-options.patch
 bugfix/all/ipc-shm-Fix-shmat-mmap-nil-page-protection.patch
+bugfix/all/sctp-avoid-BUG_ON-on-sctp_wait_for_sndbuf.patch
 
 # Fix ABI changes
 debian/of-fix-abi-changes.patch

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