From bf2acc943a45d2b2e8a9f1a5ddff6b6e43cc69d9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 29 Apr 2018 18:55:20 -0700 Subject: [PATCH] tcp: fix TCP_REPAIR_QUEUE bound checking 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 Reported-by: syzbot Cc: Pavel Emelyanov Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4b18ad41d4df..44be7f43455e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2674,7 +2674,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, case TCP_REPAIR_QUEUE: if (!tp->repair) err = -EPERM; - else if (val < TCP_QUEUES_NR) + else if ((unsigned int)val < TCP_QUEUES_NR) tp->repair_queue = val; else err = -EINVAL; -- 2.30.2