mt76: fix memcpy to potential null pointer on failed allocation

Commit Message

Colin King Dec. 14, 2017, 10:13 a.m. UTC

From: Colin Ian King <[e-mail]>

Currently if the allocation of skb fails and returns NULL then the
call to skb_put will cause a null pointer dereference. Fix this by
checking for a null skb and returning NULL.  Note that calls to
function mt76x2_mcu_msg_alloc don't directly check the null return
but instead pass the NULL pointer to mt76x2_mcu_msg_send which
checks for the NULL and returns ENOMEM in this case.

Detected by CoverityScan, CID#1462624 ("Dereference null return value")

Fixes: 7bc04215a66b ("mt76: add driver code for MT76x2e")
Signed-off-by: Colin Ian King <[e-mail]>
---
 drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Felix Fietkau Dec. 14, 2017, 10:17 a.m. UTC | #1

On 2017-12-14 11:13, Colin King wrote:
> From: Colin Ian King <[e-mail]>
> 
> Currently if the allocation of skb fails and returns NULL then the
> call to skb_put will cause a null pointer dereference. Fix this by
> checking for a null skb and returning NULL.  Note that calls to
> function mt76x2_mcu_msg_alloc don't directly check the null return
> but instead pass the NULL pointer to mt76x2_mcu_msg_send which
> checks for the NULL and returns ENOMEM in this case.
> 
> Detected by CoverityScan, CID#1462624 ("Dereference null return value")
> 
> Fixes: 7bc04215a66b ("mt76: add driver code for MT76x2e")
> Signed-off-by: Colin Ian King <[e-mail]>
Acked-by: Felix Fietkau <[e-mail]>

Kalle Valo Jan. 8, 2018, 5:28 p.m. UTC | #2

Colin Ian King <[e-mail]> wrote:

> From: Colin Ian King <[e-mail]>
> 
> Currently if the allocation of skb fails and returns NULL then the
> call to skb_put will cause a null pointer dereference. Fix this by
> checking for a null skb and returning NULL.  Note that calls to
> function mt76x2_mcu_msg_alloc don't directly check the null return
> but instead pass the NULL pointer to mt76x2_mcu_msg_send which
> checks for the NULL and returns ENOMEM in this case.
> 
> Detected by CoverityScan, CID#1462624 ("Dereference null return value")
> 
> Fixes: 7bc04215a66b ("mt76: add driver code for MT76x2e")
> Signed-off-by: Colin Ian King <[e-mail]>
> Acked-by: Felix Fietkau <[e-mail]>

Patch applied to wireless-drivers-next.git, thanks.

364bea50dbea mt76: fix memcpy to potential null pointer on failed allocation

Patch

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c b/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c
index d45737ee1412..15820b11f9db 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c
@@ -45,6 +45,8 @@  static struct sk_buff *mt76x2_mcu_msg_alloc(const void *data, int len)
 	struct sk_buff *skb;
 
 	skb = alloc_skb(len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
 	memcpy(skb_put(skb, len), data, len);
 
 	return skb;