[PATCH][next] mptcp: fix a dereference of pointer before msk is null checked.

[PATCH][next] mptcp: fix a dereference of pointer before msk is null checked.

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently the assignment of pointer net from the sock_net(sk) call
is potentially dereferencing a null pointer sk. sk points to the
same location as pointer msk and msk is being null checked after
the sock_net call.  Fix this by calling sock_net after the null
check on pointer msk.

Addresses-Coverity: ("Dereference before null check")
Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 net/mptcp/pm_netlink.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index ed60538df7b2..e76879ea5a30 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -206,13 +206,15 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 	struct mptcp_pm_add_entry *entry = from_timer(entry, timer, add_timer);
 	struct mptcp_sock *msk = entry->sock;
 	struct sock *sk = (struct sock *)msk;
-	struct net *net = sock_net(sk);
+	struct net *net;
 
 	pr_debug("msk=%p", msk);
 
 	if (!msk)
 		return;
 
+	net = sock_net(sk);
+
 	if (inet_sk_state_load(sk) == TCP_CLOSE)
 		return;
 
-- 
2.28.0

Re: [PATCH][next] mptcp: fix a dereference of pointer before msk is null checked.

[Mat Martineau]

On Mon, 9 Nov 2020, Colin King wrote:

> From: Colin Ian King <colin.king@canonical.com>
>
> Currently the assignment of pointer net from the sock_net(sk) call
> is potentially dereferencing a null pointer sk. sk points to the
> same location as pointer msk and msk is being null checked after
> the sock_net call.  Fix this by calling sock_net after the null
> check on pointer msk.
>
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> net/mptcp/pm_netlink.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>

Hi Colin and Jakub -

I noticed that the follow-up discussion on this patch didn't go to the 
netdev list, so patchwork did not get updated.

This patch is superseded by the following, which already has a Reviewed-by 
tag from Matthieu:

http://patchwork.ozlabs.org/project/netdev/patch/078a2ef5bdc4e3b2c25ef852461692001f426495.1604976945.git.geliangtang@gmail.com/


Thanks!

--
Mat Martineau
Intel

Re: [PATCH][next] mptcp: fix a dereference of pointer before msk is null checked.

[Colin Ian King]

On 11/11/2020 18:49, Mat Martineau wrote:
> On Mon, 9 Nov 2020, Colin King wrote:
> 
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Currently the assignment of pointer net from the sock_net(sk) call
>> is potentially dereferencing a null pointer sk. sk points to the
>> same location as pointer msk and msk is being null checked after
>> the sock_net call.  Fix this by calling sock_net after the null
>> check on pointer msk.
>>
>> Addresses-Coverity: ("Dereference before null check")
>> Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>> net/mptcp/pm_netlink.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
> 
> Hi Colin and Jakub -
> 
> I noticed that the follow-up discussion on this patch didn't go to the
> netdev list, so patchwork did not get updated.
> 
> This patch is superseded by the following, which already has a
> Reviewed-by tag from Matthieu:
> 
> http://patchwork.ozlabs.org/project/netdev/patch/078a2ef5bdc4e3b2c25ef852461692001f426495.1604976945.git.geliangtang@gmail.com/
> 
> 
OK, thanks for letting me know. Good to see it got fixed!

Colin
> 
> Thanks!
> 
> -- 
> Mat Martineau
> Intel