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net: Fix module refcount leak in kernel_accept()

PATCH In review Wei Yongjun 3 participants 4 messages Dec 18, 2008 – Dec 19, 2008

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Wei Yongjun

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#0 lore raw

PATCH 1/1 net: Fix module refcount leak in kernel_accept()

The kernel_accept() does not hold the module refcount of newsock->ops->owner, so we need __module_get(newsock->ops->owner) code after call kernel_accept() by hand.
In sunrpc, the module refcount is missing to hold. So this cause kernel panic.

Used following script to reproduct:

while [ 1 ];
do
mount -t nfs4 192.168.0.19:/ /mnt
touch /mnt/file
umount /mnt
lsmod | grep ipv6
done

This patch fixed the problem by add __module_get(newsock->ops->owner) to kernel_accept(). So we do not need to used __module_get(newsock->ops->owner) in every place when used kernel_accept().

Signed-off-by Wei Yongjun <[email protected]>
---
 net/bluetooth/rfcomm/core.c |    2 --
 net/socket.c                |    1 +
 2 files changed, 1 insertions(+), 2 deletions(-)
net/bluetooth/rfcomm/core.c +0 -2
index ba537fa..ce68e04 100644
@@ -1786,8 +1786,6 @@ static inline void rfcomm_accept_connection(struct rfcomm_session *s)
 	if (err < 0)
 		return;
 
-	__module_get(nsock->ops->owner);
-
 	/* Set our callbacks */
 	nsock->sk->sk_data_ready   = rfcomm_l2data_ready;
 	nsock->sk->sk_state_change = rfcomm_l2state_change;
net/socket.c +1 -0
index 92764d8..76ba80a 100644
@@ -2307,6 +2307,7 @@ int kernel_accept(struct socket *sock, struct socket **newsock, int flags)
 	}
 
 	(*newsock)->ops = sock->ops;
+	__module_get((*newsock)->ops->owner);
 
 done:
 	return err;
Signature · 1 line
1.5.3.8
maintainer
#1 lore raw

From: Wei Yongjun <[email protected]>
Date: Thu, 18 Dec 2008 18:20:46 +0800

Quoted 6 lines

The kernel_accept() does not hold the module refcount of newsock->ops->owner, so we need __module_get(newsock->ops->owner) code after call kernel_accept() by hand.
In sunrpc, the module refcount is missing to hold. So this cause kernel panic.

Used following script to reproduct:

...

Quoted 1 line
Signed-off-by Wei Yongjun <[email protected]>

Good fine, patch applied, thanks!

maintainer
#2 lore raw
In reply to Wei Yongjun

Hi Wei,

Quoted 19 lines

The kernel_accept() does not hold the module refcount of newsock->ops->owner, so we need __module_get(newsock->ops->owner) code after call kernel_accept() by hand.
In sunrpc, the module refcount is missing to hold. So this cause kernel panic.

Used following script to reproduct:

while [ 1 ];
do
mount -t nfs4 192.168.0.19:/ /mnt
touch /mnt/file
umount /mnt
lsmod | grep ipv6
done

This patch fixed the problem by add __module_get(newsock->ops->owner) to kernel_accept(). So we do not need to used __module_get(newsock->ops->owner) in every place when used kernel_accept().

Quoted 5 lines
Signed-off-by Wei Yongjun <[email protected]>
---
 net/bluetooth/rfcomm/core.c |    2 --
 net/socket.c                |    1 +
 2 files changed, 1 insertions(+), 2 deletions(-)

I was just about to reply and ask you to double check the users since I know that I am using that API. Hey, but you already did that. Thanks.

Dave, for what its worth, Acked-by me.

Regards

Marcel

maintainer
#3 lore raw

From: Marcel Holtmann <[email protected]>
Date: Fri, 19 Dec 2008 07:35:37 +0100

Quoted 21 lines

Hi Wei,

Quoted 19 lines

The kernel_accept() does not hold the module refcount of newsock->ops->owner, so we need __module_get(newsock->ops->owner) code after call kernel_accept() by hand.
In sunrpc, the module refcount is missing to hold. So this cause kernel panic.

Used following script to reproduct:

while [ 1 ];
do
mount -t nfs4 192.168.0.19:/ /mnt
touch /mnt/file
umount /mnt
lsmod | grep ipv6
done

This patch fixed the problem by add __module_get(newsock->ops->owner) to kernel_accept(). So we do not need to used __module_get(newsock->ops->owner) in every place when used kernel_accept().

Quoted 8 lines
Quoted 5 lines
Signed-off-by Wei Yongjun <[email protected]>
---
 net/bluetooth/rfcomm/core.c |    2 --
 net/socket.c                |    1 +
 2 files changed, 1 insertions(+), 2 deletions(-)

I was just about to reply and ask you to double check the users since I know that I am using that API. Hey, but you already did that. Thanks.

That's the exact audit I did before applying his patch :-)