From: Arnaldo Carvalho de Melo acme@redhat.com
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit d5afb6f9b6bb2c57bd0c05e76e12489dc0d037d9 ]
The code where sk_clone() came from created a new socket and locked it, but then, on the error path didn't unlock it.
This problem stayed there for a long while, till b0691c8ee7c2 ("net: Unlock sock before calling sk_free()") fixed it, but unfortunately the callers of sk_clone() (now sk_clone_locked()) were not audited and the one in dccp_create_openreq_child() remained.
Now in the age of the syskaller fuzzer, this was finally uncovered, as reported by Dmitry:
---- 8< ----
I've got the following report while running syzkaller fuzzer on 86292b33d4b7 ("Merge branch 'akpm' (patches from Andrew)")
[ BUG: held lock freed! ] 4.10.0+ #234 Not tainted ------------------------- syz-executor6/6898 is freeing memory ffff88006286cac0-ffff88006286d3b7, with a lock still held there! (slock-AF_INET6){+.-...}, at: [<ffffffff8362c2c9>] spin_lock include/linux/spinlock.h:299 [inline] (slock-AF_INET6){+.-...}, at: [<ffffffff8362c2c9>] sk_clone_lock+0x3d9/0x12c0 net/core/sock.c:1504 5 locks held by syz-executor6/6898: #0: (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff839a34b4>] lock_sock include/net/sock.h:1460 [inline] #0: (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff839a34b4>] inet_stream_connect+0x44/0xa0 net/ipv4/af_inet.c:681 #1: (rcu_read_lock){......}, at: [<ffffffff83bc1c2a>] inet6_csk_xmit+0x12a/0x5d0 net/ipv6/inet6_connection_sock.c:126 #2: (rcu_read_lock){......}, at: [<ffffffff8369b424>] __skb_unlink include/linux/skbuff.h:1767 [inline] #2: (rcu_read_lock){......}, at: [<ffffffff8369b424>] __skb_dequeue include/linux/skbuff.h:1783 [inline] #2: (rcu_read_lock){......}, at: [<ffffffff8369b424>] process_backlog+0x264/0x730 net/core/dev.c:4835 #3: (rcu_read_lock){......}, at: [<ffffffff83aeb5c0>] ip6_input_finish+0x0/0x1700 net/ipv6/ip6_input.c:59 #4: (slock-AF_INET6){+.-...}, at: [<ffffffff8362c2c9>] spin_lock include/linux/spinlock.h:299 [inline] #4: (slock-AF_INET6){+.-...}, at: [<ffffffff8362c2c9>] sk_clone_lock+0x3d9/0x12c0 net/core/sock.c:1504
Fix it just like was done by b0691c8ee7c2 ("net: Unlock sock before calling sk_free()").
Reported-by: Dmitry Vyukov dvyukov@google.com Cc: Cong Wang xiyou.wangcong@gmail.com Cc: Eric Dumazet edumazet@google.com Cc: Gerrit Renker gerrit@erg.abdn.ac.uk Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/20170301153510.GE15145@kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- net/dccp/minisocks.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c index 838f524cf11a..53c38641fe98 100644 --- a/net/dccp/minisocks.c +++ b/net/dccp/minisocks.c @@ -122,6 +122,7 @@ struct sock *dccp_create_openreq_child(struct sock *sk, /* It is still raw copy of parent, so invalidate * destructor and make plain sk_free() */ newsk->sk_destruct = NULL; + bh_unlock_sock(newsk); sk_free(newsk); return NULL; }