[PATCH] can: j1939: prevent allocation of j1939 filter for optlen = 0

[PATCH] can: j1939: prevent allocation of j1939 filter for optlen = 0

[Norbert Slusarek]

If optval != NULL and optlen = 0 are specified for SO_J1939_FILTER in
j1939_sk_setsockopt(), memdup_sockptr() will return ZERO_PTR for 0 size
allocation. The new filter will be mistakenly assigned ZERO_PTR.
This patch checks for optlen != 0 and filter will be assigned NULL
in case of optlen = 0.

Fixes: a7b75c5a8c41 ("net: pass a sockptr_t into ->setsockopt")
Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>

---
 net/can/j1939/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 56aa66147d5a..ff20cb629200 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -673,7 +673,7 @@ static int j1939_sk_setsockopt(struct socket *sock, int level, int optname,

 	switch (optname) {
 	case SO_J1939_FILTER:
-		if (!sockptr_is_null(optval)) {
+		if (!sockptr_is_null(optval) && optlen != 0) {
 			struct j1939_filter *f;
 			int c;

--
2.30.2

Re: [PATCH] can: j1939: prevent allocation of j1939 filter for optlen = 0

[Oleksij Rempel]

Hi Norbert,

On Sun, Jun 20, 2021 at 02:38:42PM +0200, Norbert Slusarek wrote:
> If optval != NULL and optlen = 0 are specified for SO_J1939_FILTER in
> j1939_sk_setsockopt(), memdup_sockptr() will return ZERO_PTR for 0 size
> allocation. The new filter will be mistakenly assigned ZERO_PTR.
> This patch checks for optlen != 0 and filter will be assigned NULL
> in case of optlen = 0.
> 
> Fixes: a7b75c5a8c41 ("net: pass a sockptr_t into ->setsockopt")
> Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

Thank you!

> ---
>  net/can/j1939/socket.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
> index 56aa66147d5a..ff20cb629200 100644
> --- a/net/can/j1939/socket.c
> +++ b/net/can/j1939/socket.c
> @@ -673,7 +673,7 @@ static int j1939_sk_setsockopt(struct socket *sock, int level, int optname,
> 
>  	switch (optname) {
>  	case SO_J1939_FILTER:
> -		if (!sockptr_is_null(optval)) {
> +		if (!sockptr_is_null(optval) && optlen != 0) {
>  			struct j1939_filter *f;
>  			int c;
> 
> --
> 2.30.2
> 
> 

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Re: [PATCH] can: j1939: prevent allocation of j1939 filter for optlen = 0

[Marc Kleine-Budde]

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On 20.06.2021 14:38:42, Norbert Slusarek wrote:
> If optval != NULL and optlen = 0 are specified for SO_J1939_FILTER in
> j1939_sk_setsockopt(), memdup_sockptr() will return ZERO_PTR for 0 size
> allocation. The new filter will be mistakenly assigned ZERO_PTR.
> This patch checks for optlen != 0 and filter will be assigned NULL
> in case of optlen = 0.
> 
> Fixes: a7b75c5a8c41 ("net: pass a sockptr_t into ->setsockopt")
> Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>

The problem was in the initial commit, too. Changed Fixes tags
accordingly to:

| Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")

applied to linux-can/testing

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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