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

[PATCH] 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

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 net/l2tp/l2tp_ip.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 585d93e..a4d8364 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -442,8 +442,10 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
 
 		daddr = lip->l2tp_addr.s_addr;
 	} else {
-		if (sk->sk_state != TCP_ESTABLISHED)
-			return -EDESTADDRREQ;
+		if (sk->sk_state != TCP_ESTABLISHED) {
+			rc = -EDESTADDRREQ;
+			goto out;
+		}
 
 		daddr = inet->inet_daddr;
 		connected = 1;
-- 
1.7.8.5

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

[Eric Dumazet]

On Wed, 2012-05-02 at 15:10 +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
> 
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---
>  net/l2tp/l2tp_ip.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
> index 585d93e..a4d8364 100644
> --- a/net/l2tp/l2tp_ip.c
> +++ b/net/l2tp/l2tp_ip.c
> @@ -442,8 +442,10 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
>  
>  		daddr = lip->l2tp_addr.s_addr;
>  	} else {
> -		if (sk->sk_state != TCP_ESTABLISHED)
> -			return -EDESTADDRREQ;
> +		if (sk->sk_state != TCP_ESTABLISHED) {
> +			rc = -EDESTADDRREQ;
> +			goto out;
> +		}
>  
>  		daddr = inet->inet_daddr;
>  		connected = 1;

Good catch, but please use existing code style in this function.

rc = -EDESTADDRREQ;
if (sk->sk_state != TCP_ESTABLISHED)
	goto out;

Also, please add in your commit message bug origin to ease stable team
work (not counting reviewers work)

Bug added in commit 2f16270f41e1 (l2tp: Fix locking in l2tp_ip.c)

Really, given the amount of patches you already sent, you should already
know that.

Thanks

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

[Sasha Levin]

On Wed, May 2, 2012 at 3:28 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Good catch, but please use existing code style in this function.
>
> rc = -EDESTADDRREQ;
> if (sk->sk_state != TCP_ESTABLISHED)
>        goto out;
>
> Also, please add in your commit message bug origin to ease stable team
> work (not counting reviewers work)
>
> Bug added in commit 2f16270f41e1 (l2tp: Fix locking in l2tp_ip.c)
>
> Really, given the amount of patches you already sent, you should already
> know that.
>
> Thanks
>
>

Understood. I'll resend.