4.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Hannes Frederic Sowa <[email protected]> [ Upstream commit 8844f97238ca6c1ca92a5d6c69f53efd361a266f ] In case multiple writes to a unix stream socket race we could end up in a situation where we pre-allocate a new skb for use in unix_stream_sendpage but have to free it again in the locked section because another skb has been appended meanwhile, which we must use. Accidentally we didn't clear the pointer after consuming it and so we touched freed memory while appending it to the sk_receive_queue. So, clear the pointer after consuming the skb. This bug has been found with syzkaller (http://github.com/google/syzkaller) by Dmitry Vyukov. Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support") Reported-by: Dmitry Vyukov <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Eric Dumazet <[email protected]> Signed-off-by: Hannes Frederic Sowa <[email protected]> Acked-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/unix/af_unix.c | 1 + 1 file changed, 1 insertion(+) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1799,6 +1799,7 @@ alloc_skb: * this - does no harm */ consume_skb(newskb); + newskb = NULL; } if (skb_append_pagefrags(skb, page, offset, size)) { -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
