From: Eric Dumazet <eduma...@google.com>
Date: Sun, 29 Apr 2018 18:55:20 -0700
> syzbot is able to produce a nasty WARN_ON() in tcp_verify_left_out()
> with following C-repro :
>
> socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 3
> setsockopt(3, SOL_TCP, TCP_REPAIR, [1], 4) = 0
> setsockopt(3, SOL_TCP, TCP_REPAIR_QUEUE, [-1], 4) = 0
> bind(3, {sa_family=AF_INET, sin_port=htons(20002),
> sin_addr=inet_addr("0.0.0.0")}, 16) = 0
> sendto(3,
> "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
> 1242, MSG_FASTOPEN, {sa_family=AF_INET, sin_port=htons(20002),
> sin_addr=inet_addr("127.0.0.1")}, 16) = 1242
> setsockopt(3, SOL_TCP, TCP_REPAIR_WINDOW,
> "\4\0\0@+\205\0\0\377\377\0\0\377\377\377\177\0\0\0\0", 20) = 0
> writev(3, [{"\270", 1}], 1) = 1
> setsockopt(3, SOL_TCP, TCP_REPAIR_OPTIONS,
> "\10\0\0\0\0\0\0\0\0\0\0\0|\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 386) = > 0
> writev(3,
> [{"\210v\r[\226\320t\231qwQ\204\264l\254\t\1\20\245\214p\350H\223\254;\\\37\345\307p$"...,
> 3144}], 1) = 3144
>
> The 3rd system call looks odd :
> setsockopt(3, SOL_TCP, TCP_REPAIR_QUEUE, [-1], 4) = 0
>
> This patch makes sure bound checking is using an unsigned compare.
>
> Fixes: ee9952831cfd ("tcp: Initial repair mode")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Reported-by: syzbot <syzkal...@googlegroups.com>
Ouch.
Applied and queued up for -stable, thanks Eric.
