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Arnaldo Carvalho de Melo authored
commit 34b88a68 upstream. The syzkaller fuzzer hit the following use-after-free: Call Trace: [<ffffffff8175ea0e>] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:295 [<ffffffff851cc31a>] __sys_recvmmsg+0x6fa/0x7f0 net/socket.c:2261 [< inline >] SYSC_recvmmsg net/socket.c:2281 [<ffffffff851cc57f>] SyS_recvmmsg+0x16f/0x180 net/socket.c:2270 [<ffffffff86332bb6>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 And, as Dmitry rightly assessed, that is because we can drop the reference and then touch it when the underlying recvmsg calls return some packets and then hit an error, which will make recvmmsg to set sock->sk->sk_err, oops, fix it. Reported-and-Tested-by:
Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Fixes: a2e27255 ("net: Introduce recvmmsg socket syscall") http://lkml.kernel.org/r/20160122211644.GC2470@redhat.comSigned-off-by:
Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
Ben Hutchings <ben@decadent.org.uk>
fc49d04a