2017-09-08 15:02:43

by Colin King

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

From: Colin Ian King <[email protected]>

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 <[email protected]>
---
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

2017-09-08 17:46:28

by Oliver Hartkopp

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

On 09/08/2017 05:02 PM, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> 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 <[email protected]>

Acked-by: Oliver Hartkopp <[email protected]>


Thanks Collin!

> ---
> 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. */
>