net: core: Prevent from dereferencing null pointer when releasing SKB

myunghoj · davem330 · commit 9899886d5e8e · 2017-04-26T14:47:14.000-04:00
Added NULL check to make __dev_kfree_skb_irq consistent with kfree family of functions. Link: https://bugzilla.kernel.org/show_bug.cgi?id=195289 Signed-off-by: Myungho Jung <mhjungk@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
@@ -2450,6 +2450,9 @@ void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
 {
 	unsigned long flags;
 
+	if (unlikely(!skb))
+		return;
+
 	if (likely(atomic_read(&skb->users) == 1)) {
 		smp_rmb();
 		atomic_set(&skb->users, 0);

Original file line number	Diff line number	Diff line change
`@@ -2450,6 +2450,9 @@ void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)`
`2450`	`2450`	`{`
`2451`	`2451`	`unsigned long flags;`
`2452`	`2452`
	`2453`	`+ if (unlikely(!skb))`
	`2454`	`+ return;`
	`2455`	`+`
`2453`	`2456`	`if (likely(atomic_read(&skb->users) == 1)) {`
`2454`	`2457`	`smp_rmb();`
`2455`	`2458`	`atomic_set(&skb->users, 0);`