Commit 77c1090f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

net: fix infinite loop in __skb_recv_datagram()

Tommi was fuzzing with trinity and reported the following problem :

commit 3f518bf7 (datagram: Add offset argument to __skb_recv_datagram)
missed that a raw socket receive queue can contain skbs with no payload.

We can loop in __skb_recv_datagram() with MSG_PEEK mode, because
wait_for_packet() is not prepared to skip these skbs.

[   83.541011] INFO: rcu_sched detected stalls on CPUs/tasks: {}
(detected by 0, t=26002 jiffies, g=27673, c=27672, q=75)
[   83.541011] INFO: Stall ended before state dump start
[  108.067010] BUG: soft lockup - CPU#0 stuck for 22s! [trinity-child31:2847]
...
[  108.067010] Call Trace:
[  108.067010]  [<ffffffff818cc103>] __skb_recv_datagram+0x1a3/0x3b0
[  108.067010]  [<ffffffff818cc33d>] skb_recv_datagram+0x2d/0x30
[  108.067010]  [<ffffffff819ed43d>] rawv6_recvmsg+0xad/0x240
[  108.067010]  [<ffffffff818c4b04>] sock_common_recvmsg+0x34/0x50
[  108.067010]  [<ffffffff818bc8ec>] sock_recvmsg+0xbc/0xf0
[  108.067010]  [<ffffffff818bf31e>] sys_recvfrom+0xde/0x150
[  108.067010]  [<ffffffff81ca4329>] system_call_fastpath+0x16/0x1b
Reported-by: default avatarTommi Rantala <tt.rantala@gmail.com>
Tested-by: default avatarTommi Rantala <tt.rantala@gmail.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Acked-by: default avatarPavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1bf014e5
...@@ -187,7 +187,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, ...@@ -187,7 +187,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
skb_queue_walk(queue, skb) { skb_queue_walk(queue, skb) {
*peeked = skb->peeked; *peeked = skb->peeked;
if (flags & MSG_PEEK) { if (flags & MSG_PEEK) {
if (*off >= skb->len) { if (*off >= skb->len && skb->len) {
*off -= skb->len; *off -= skb->len;
continue; continue;
} }
......
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