diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-10-19 19:40:39 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-22 03:45:52 +0300 |
| commit | 54d431176429e9cf064461589e5174349a9f73da (patch) | |
| tree | e67d98437ea56d6872670cfccc7ae660d2fdcf24 | |
| parent | d2b2762433435d81fe76be6d16078c436b45cf3b (diff) | |
| download | linux-54d431176429e9cf064461589e5174349a9f73da.tar.xz | |
sock: correct sk_wmem_queued accounting on efault in tcp zerocopy
Syzkaller hits WARN_ON(sk->sk_wmem_queued) in sk_stream_kill_queues
after triggering an EFAULT in __zerocopy_sg_from_iter.
On this error, skb_zerocopy_stream_iter resets the skb to its state
before the operation with __pskb_trim. It cannot kfree_skb like
datagram callers, as the skb may have data from a previous send call.
__pskb_trim calls skb_condense for unowned skbs, which adjusts their
truesize. These tcp skbuffs are owned and their truesize must add up
to sk_wmem_queued. But they match because their skb->sk is NULL until
tcp_transmit_skb.
Temporarily set skb->sk when calling __pskb_trim to signal that the
skbuffs are owned and avoid the skb_condense path.
Fixes: 52267790ef52 ("sock: add MSG_ZEROCOPY")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/skbuff.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index e62476beee95..24656076906d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1124,9 +1124,13 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb, err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len); if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) { + struct sock *save_sk = skb->sk; + /* Streams do not free skb on error. Reset to prev state. */ msg->msg_iter = orig_iter; + skb->sk = sk; ___pskb_trim(skb, orig_len); + skb->sk = save_sk; return err; } |