From: Steven J. Magnani <steve@digidescorp.com>
Date: Tue, 30 Mar 2010 20:56:01 +0000 (-0700)
Subject: net: Fix oops from tcp_collapse() when using splice()
X-Git-Tag: firefly_0821_release~10186^2~920
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=12fc5c218002041cf2d3be3a5fd26fad993c6fbc;p=firefly-linux-kernel-4.4.55.git

net: Fix oops from tcp_collapse() when using splice()

[ Upstream commit baff42ab1494528907bf4d5870359e31711746ae ]

tcp_read_sock() can have a eat skbs without immediately advancing copied_seq.
This can cause a panic in tcp_collapse() if it is called as a result
of the recv_actor dropping the socket lock.

A userspace program that splices data from a socket to either another
socket or to a file can trigger this bug.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0df6fc0e8a53..108fad073194 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1335,6 +1335,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
 		sk_eat_skb(sk, skb, 0);
 		if (!desc->count)
 			break;
+		tp->copied_seq = seq;
 	}
 	tp->copied_seq = seq;