[PATCH] can: check for null sk before deferencing it via the call to sock_net

Subsystems: can network layer, the rest

STALE3243d

5 messages, 4 authors, 2017-10-17 · open the first message on its own page

[PATCH] can: check for null sk before deferencing it via the call to sock_net

From: Colin King <hidden>
Date: 2017-09-08 15:02:43

From: Colin Ian King <redacted>

The assignment of net via call sock_net will dereference sk. This
is performed before a sanity null check on sk, so there could be
a potential null dereference on the sock_net call if sk is null.
Fix this by assigning net after the sk null check. Also replace
the sk == NULL with the more usual !sk idiom.

Detected by CoverityScan CID#1431862 ("Dereference before null check")

Fixes: 384317ef4187 ("can: network namespace support for CAN_BCM protocol")
Signed-off-by: Colin Ian King <redacted>
---
 net/can/bcm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 47a8748d953a..a3791674b8ce 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c

@@ -1493,13 +1493,14 @@ static int bcm_init(struct sock *sk)
 static int bcm_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
-	struct net *net = sock_net(sk);
+	struct net *net;
 	struct bcm_sock *bo;
 	struct bcm_op *op, *next;
 
-	if (sk == NULL)
+	if (!sk)
 		return 0;
 
+	net = sock_net(sk);
 	bo = bcm_sk(sk);
 
 	/* remove bcm_ops, timer, rx_unregister(), etc. */

-- 
2.14.1

Re: [PATCH] can: check for null sk before deferencing it via the call to sock_net

From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: 2017-09-08 17:46:28


On 09/08/2017 05:02 PM, Colin King wrote:

From: Colin Ian King <redacted>

The assignment of net via call sock_net will dereference sk. This
is performed before a sanity null check on sk, so there could be
a potential null dereference on the sock_net call if sk is null.
Fix this by assigning net after the sk null check. Also replace
the sk == NULL with the more usual !sk idiom.

Detected by CoverityScan CID#1431862 ("Dereference before null check")

Fixes: 384317ef4187 ("can: network namespace support for CAN_BCM protocol")
Signed-off-by: Colin Ian King <redacted>

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>


Thanks Collin!

quoted hunk

---
  net/can/bcm.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 47a8748d953a..a3791674b8ce 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c

@@ -1493,13 +1493,14 @@ static int bcm_init(struct sock *sk)
  static int bcm_release(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
-	struct net *net = sock_net(sk);
+	struct net *net;
  	struct bcm_sock *bo;
  	struct bcm_op *op, *next;
  
-	if (sk == NULL)
+	if (!sk)
  		return 0;
  
+	net = sock_net(sk);
  	bo = bcm_sk(sk);
  
  	/* remove bcm_ops, timer, rx_unregister(), etc. */

Re: [PATCH] can: check for null sk before deferencing it via the call to sock_net

From: Josh Boyer <hidden>
Date: 2017-10-16 16:37:13

On Fri, Sep 8, 2017 at 1:46 PM, Oliver Hartkopp [off-list ref] wrote:


On 09/08/2017 05:02 PM, Colin King wrote:

quoted

From: Colin Ian King <redacted>

The assignment of net via call sock_net will dereference sk. This
is performed before a sanity null check on sk, so there could be
a potential null dereference on the sock_net call if sk is null.
Fix this by assigning net after the sk null check. Also replace
the sk == NULL with the more usual !sk idiom.

Detected by CoverityScan CID#1431862 ("Dereference before null check")

Fixes: 384317ef4187 ("can: network namespace support for CAN_BCM
protocol")
Signed-off-by: Colin Ian King <redacted>


Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>

I don't see this one queued up in the net or net-next trees.  Did it
fall through the cracks or did it get queued up elsewhere?  Seems like
it's a good candidate to get into 4.14?

josh


Thanks Collin!

quoted

---
  net/can/bcm.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 47a8748d953a..a3791674b8ce 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c

@@ -1493,13 +1493,14 @@ static int bcm_init(struct sock *sk)
  static int bcm_release(struct socket *sock)
  {
        struct sock *sk = sock->sk;
-       struct net *net = sock_net(sk);
+       struct net *net;
        struct bcm_sock *bo;
        struct bcm_op *op, *next;
  -     if (sk == NULL)
+       if (!sk)
                return 0;
  +     net = sock_net(sk);
        bo = bcm_sk(sk);
        /* remove bcm_ops, timer, rx_unregister(), etc. */

Re: [PATCH] can: check for null sk before deferencing it via the call to sock_net

From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: 2017-10-16 17:35:43

On 10/16/2017 06:37 PM, Josh Boyer wrote:

On Fri, Sep 8, 2017 at 1:46 PM, Oliver Hartkopp [off-list ref] wrote:

quoted


On 09/08/2017 05:02 PM, Colin King wrote:

quoted

From: Colin Ian King <redacted>

The assignment of net via call sock_net will dereference sk. This
is performed before a sanity null check on sk, so there could be
a potential null dereference on the sock_net call if sk is null.
Fix this by assigning net after the sk null check. Also replace
the sk == NULL with the more usual !sk idiom.

Detected by CoverityScan CID#1431862 ("Dereference before null check")

Fixes: 384317ef4187 ("can: network namespace support for CAN_BCM
protocol")
Signed-off-by: Colin Ian King <redacted>


Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>

I don't see this one queued up in the net or net-next trees.  Did it
fall through the cracks or did it get queued up elsewhere?  Seems like
it's a good candidate to get into 4.14?

It definitely is!

Marc is our responsible guy for CAN related upstreams - but he seems to 
be busy as I already poked him here:

https://marc.info/?l=linux-can&m=150771819505097&w=2

If he doesn't send a pull request by beginning of next week, I would ask 
Dave to grab these patches - to get them into 4.14.

Best regards,
Oliver

Re: [PATCH] can: check for null sk before deferencing it via the call to sock_net

From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: 2017-10-17 10:28:37

On 09/08/2017 05:02 PM, Colin King wrote:

From: Colin Ian King <redacted>

The assignment of net via call sock_net will dereference sk. This
is performed before a sanity null check on sk, so there could be
a potential null dereference on the sock_net call if sk is null.
Fix this by assigning net after the sk null check. Also replace
the sk == NULL with the more usual !sk idiom.

Detected by CoverityScan CID#1431862 ("Dereference before null check")

Fixes: 384317ef4187 ("can: network namespace support for CAN_BCM protocol")
Signed-off-by: Colin Ian King <redacted>

Applied to can.

Tnx,
Marc

-- 
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