Netdev fix race in resq_queue_unlink

2 files changed, 81 insertions, 0 deletions

diff --git a/kernel.spec b/kernel.spec
index 320e3c0ff..110cafdcc 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -636,6 +636,8 @@ Patch529: vfs-Test-for-and-handle-paths-that-are-unreachable-f.patch
 #CVE-2015-7613 rhbz 1268270 1268273
 Patch532: Initialize-msg-shm-IPC-objects-before-doing-ipc_addi.patch
 
+Patch533: net-inet-fix-race-in-reqsk_queue_unlink.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1391,6 +1393,8 @@ ApplyPatch vfs-Test-for-and-handle-paths-that-are-unreachable-f.patch
 #CVE-2015-7613 rhbz 1268270 1268273
 ApplyPatch Initialize-msg-shm-IPC-objects-before-doing-ipc_addi.patch
 
+ApplyPatch net-inet-fix-race-in-reqsk_queue_unlink.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2243,6 +2247,7 @@ fi
 %changelog
 * Mon Oct 05 2015 Justin M. Forbes <jforbes@fedoraproject.org>
 - Linux v4.2.3
+- Netdev fix race in resq_queue_unlink
 
 * Fri Oct 02 2015 Josh Boyer <jwboyer@fedoraproject.org>
 - CVE-2015-7613 Unauthorized access to IPC via SysV shm (rhbz 1268270 1268273)
diff --git a/net-inet-fix-race-in-reqsk_queue_unlink.patch b/net-inet-fix-race-in-reqsk_queue_unlink.patch
new file mode 100644
index 000000000..744084314
--- /dev/null
+++ b/net-inet-fix-race-in-reqsk_queue_unlink.patch
@@ -0,0 +1,76 @@
+From patchwork Thu Oct  1 12:39:26 2015
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [net] inet: fix race in reqsk_queue_unlink()
+From: Eric Dumazet <eric.dumazet@gmail.com>
+X-Patchwork-Id: 524966
+Message-Id: <1443703166.32531.47.camel@edumazet-glaptop2.roam.corp.google.com>
+To: David Miller <davem@davemloft.net>
+Cc: netdev <netdev@vger.kernel.org>, Yuchung Cheng <ycheng@google.com>
+Date: Thu, 01 Oct 2015 05:39:26 -0700
+
+From: Eric Dumazet <edumazet@google.com>
+
+reqsk_timer_handler() tests if icsk_accept_queue.listen_opt
+is NULL at its beginning.
+
+By the time it calls inet_csk_reqsk_queue_drop() and
+reqsk_queue_unlink(), listener might have been closed and
+inet_csk_listen_stop() had called reqsk_queue_yank_acceptq()
+which sets icsk_accept_queue.listen_opt to NULL
+
+We therefore need to correctly check listen_opt being NULL
+after holding syn_wait_lock for proper synchronization.
+
+Fixes: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer")
+Fixes: b357a364c57c ("inet: fix possible panic in reqsk_queue_unlink()")
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Cc: Yuchung Cheng <ycheng@google.com>
+---
+ net/ipv4/inet_connection_sock.c |   19 ++++++++++---------
+ 1 file changed, 10 insertions(+), 9 deletions(-)
+
+
+
+--
+To unsubscribe from this list: send the line "unsubscribe netdev" in
+the body of a message to majordomo@vger.kernel.org
+More majordomo info at  http://vger.kernel.org/majordomo-info.html
+
+diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
+index 7bb9c39e0a4d..61b45a17fc73 100644
+--- a/net/ipv4/inet_connection_sock.c
++++ b/net/ipv4/inet_connection_sock.c
+@@ -577,21 +577,22 @@ EXPORT_SYMBOL(inet_rtx_syn_ack);
+ static bool reqsk_queue_unlink(struct request_sock_queue *queue,
+ 			       struct request_sock *req)
+ {
+-	struct listen_sock *lopt = queue->listen_opt;
+ 	struct request_sock **prev;
++	struct listen_sock *lopt;
+ 	bool found = false;
+ 
+ 	spin_lock(&queue->syn_wait_lock);
+-
+-	for (prev = &lopt->syn_table[req->rsk_hash]; *prev != NULL;
+-	     prev = &(*prev)->dl_next) {
+-		if (*prev == req) {
+-			*prev = req->dl_next;
+-			found = true;
+-			break;
++	lopt = queue->listen_opt;
++	if (lopt) {
++		for (prev = &lopt->syn_table[req->rsk_hash]; *prev != NULL;
++		     prev = &(*prev)->dl_next) {
++			if (*prev == req) {
++				*prev = req->dl_next;
++				found = true;
++				break;
++			}
+ 		}
+ 	}
+-
+ 	spin_unlock(&queue->syn_wait_lock);
+ 	if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
+ 		reqsk_put(req);