filter: use size of fetched data in __load_pointer() (4bc65dd8) · Commits · 戴 / test

__load_pointer() checks data we fetch from skb is included in head portion, but assumes we fetch one byte, instead of up to four. This wont crash because we have extra bytes (struct skb_shared_info) after head, but this can read uninitialized bytes. Fix this using size of the data (1, 2, 4 bytes) in the test. Signed-off-by:

Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/filter.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -88,7 +88,7 @@ enum {
		};

		/* No hurry in this branch */
		static void __load_pointer(const struct sk_buff skb, int k)
		static void __load_pointer(const struct sk_buff skb, int k, unsigned int size)
		{
		u8 *ptr = NULL;

		@@ -97,7 +97,7 @@ static void __load_pointer(const struct sk_buff skb, int k)
		else if (k >= SKF_LL_OFF)
		ptr = skb_mac_header(skb) + k - SKF_LL_OFF;

		if (ptr >= skb->head && ptr < skb_tail_pointer(skb))
		if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
		return ptr;
		return NULL;
		}
		@@ -110,7 +110,7 @@ static inline void load_pointer(const struct sk_buff skb, int k,
		else {
		if (k >= SKF_AD_OFF)
		return NULL;
		return __load_pointer(skb, k);
		return __load_pointer(skb, k, size);
		}
		}

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