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

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Submitter Steven J. Magnani
Date March 30, 2010, 8:45 p.m.
Message ID <1269981913-18073-1-git-send-email-steve@digidescorp.com>
Download mbox | patch
Permalink /patch/49051/
State Accepted
Delegated to: David Miller
Headers show

Comments

Steven J. Magnani - March 30, 2010, 8:45 p.m.
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>
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David Miller - March 30, 2010, 8:47 p.m.
From: "Steven J. Magnani" <steve@digidescorp.com>
Date: Tue, 30 Mar 2010 15:45:13 -0500

> 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>

Thanks for fixing this I'll look at your patch more closely
right now.
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David Miller - March 30, 2010, 8:56 p.m.
From: David Miller <davem@davemloft.net>
Date: Tue, 30 Mar 2010 13:47:41 -0700 (PDT)

> From: "Steven J. Magnani" <steve@digidescorp.com>
> Date: Tue, 30 Mar 2010 15:45:13 -0500
> 
>> 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>
> 
> Thanks for fixing this I'll look at your patch more closely
> right now.

Patch applied, thanks Steven!
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Patch

diff -uprN a/net/ipv4/tcp.c b/net/ipv4/tcp.c
--- a/net/ipv4/tcp.c	2010-03-30 15:25:55.000000000 -0500
+++ b/net/ipv4/tcp.c	2010-03-30 15:27:49.000000000 -0500
@@ -1335,6 +1335,7 @@  int tcp_read_sock(struct sock *sk, read_
 		sk_eat_skb(sk, skb, 0);
 		if (!desc->count)
 			break;
+		tp->copied_seq = seq;
 	}
 	tp->copied_seq = seq;