[PATCH v2] net: l2tp: unlock socket lock before returning from l2tp_ip_sendmsg

[PATCH v2] net: l2tp: unlock socket lock before returning from l2tp_ip_sendmsg

[Sasha Levin]

l2tp_ip_sendmsg could return without releasing socket lock, making it all the
way to userspace, and generating the following warning:

[  130.891594] ================================================
[  130.894569] [ BUG: lock held when returning to user space! ]
[  130.897257] 3.4.0-rc5-next-20120501-sasha #104 Tainted: G        W
[  130.900336] ------------------------------------------------
[  130.902996] trinity/8384 is leaving the kernel with locks still held!
[  130.906106] 1 lock held by trinity/8384:
[  130.907924]  #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff82b9503f>] l2tp_ip_sendmsg+0x2f/0x550

Introduced by commit 2f16270 ("l2tp: Fix locking in l2tp_ip.c").

Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 net/l2tp/l2tp_ip.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 585d93e..6274f0b 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -442,8 +442,9 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
 
 		daddr = lip->l2tp_addr.s_addr;
 	} else {
+		rc = -EDESTADDRREQ;
 		if (sk->sk_state != TCP_ESTABLISHED)
-			return -EDESTADDRREQ;
+			goto out;
 
 		daddr = inet->inet_daddr;
 		connected = 1;
-- 
1.7.8.5

Re: [PATCH v2] net: l2tp: unlock socket lock before returning from l2tp_ip_sendmsg

[Eric Dumazet]

On Wed, 2012-05-02 at 15:58 +0200, Sasha Levin wrote:
> l2tp_ip_sendmsg could return without releasing socket lock, making it all the
> way to userspace, and generating the following warning:
> 
> [  130.891594] ================================================
> [  130.894569] [ BUG: lock held when returning to user space! ]
> [  130.897257] 3.4.0-rc5-next-20120501-sasha #104 Tainted: G        W
> [  130.900336] ------------------------------------------------
> [  130.902996] trinity/8384 is leaving the kernel with locks still held!
> [  130.906106] 1 lock held by trinity/8384:
> [  130.907924]  #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff82b9503f>] l2tp_ip_sendmsg+0x2f/0x550
> 
> Introduced by commit 2f16270 ("l2tp: Fix locking in l2tp_ip.c").
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---

Oh well, please read Documentation/stable_kernel_rules.txt

Also, David prefers to handle stable submissions himself for net tree.

Anyway :

Acked-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH v2] net: l2tp: unlock socket lock before returning from l2tp_ip_sendmsg

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 02 May 2012 16:32:36 +0200

> On Wed, 2012-05-02 at 15:58 +0200, Sasha Levin wrote:
>> l2tp_ip_sendmsg could return without releasing socket lock, making it all the
>> way to userspace, and generating the following warning:
>> 
>> [  130.891594] ================================================
>> [  130.894569] [ BUG: lock held when returning to user space! ]
>> [  130.897257] 3.4.0-rc5-next-20120501-sasha #104 Tainted: G        W
>> [  130.900336] ------------------------------------------------
>> [  130.902996] trinity/8384 is leaving the kernel with locks still held!
>> [  130.906106] 1 lock held by trinity/8384:
>> [  130.907924]  #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff82b9503f>] l2tp_ip_sendmsg+0x2f/0x550
>> 
>> Introduced by commit 2f16270 ("l2tp: Fix locking in l2tp_ip.c").
>> 
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
>> ---
> 
> Oh well, please read Documentation/stable_kernel_rules.txt
> 
> Also, David prefers to handle stable submissions himself for net tree.
> 
> Anyway :
> 
> Acked-by: Eric Dumazet <edumazet@google.com>

Applied.