Messages in this thread | | | Subject | Re: [PATCH 4.4 stable net] net: tcp: Fix use-after-free in tcp_write_xmit | From | Eric Dumazet <> | Date | Thu, 25 Jul 2019 08:19:52 +0200 |
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On 7/25/19 6:29 AM, maowenan wrote: >
>>>>> Syzkaller reproducer(): >>>>> r0 = socket$packet(0x11, 0x3, 0x300) >>>>> r1 = socket$inet_tcp(0x2, 0x1, 0x0) >>>>> bind$inet(r1, &(0x7f0000000300)={0x2, 0x4e21, @multicast1}, 0x10) >>>>> connect$inet(r1, &(0x7f0000000140)={0x2, 0x1000004e21, @loopback}, 0x10) >>>>> recvmmsg(r1, &(0x7f0000001e40)=[{{0x0, 0x0, &(0x7f0000000100)=[{&(0x7f00000005c0)=""/88, 0x58}], 0x1}}], 0x1, 0x40000000, 0x0) >>>>> sendto$inet(r1, &(0x7f0000000000)="e2f7ad5b661c761edf", 0x9, 0x8080, 0x0, 0x0) >>>>> r2 = fcntl$dupfd(r1, 0x0, r0) >>>>> connect$unix(r2, &(0x7f00000001c0)=@file={0x0, './file0\x00'}, 0x6e) >>>>> >> >> It does call tcp_disconnect(), by one of the connect() call. > > yes, __inet_stream_connect will call tcp_disconnect when sa_family == AF_UNSPEC, in c repro if it > passes sa_family with AF_INET it won't call disconnect, and then sk_send_head won't be NULL when tcp_connect. >
Look again at the Syzkaller reproducer()
It definitely uses tcp_disconnect()
Do not be fooled by connect$unix(), this is a connect() call really, with AF_UNSPEC
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