From 4bc65dd8d88671712d71592a83374cfb0b5fce7a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 7 Dec 2010 22:26:15 +0000 Subject: [PATCH] filter: use size of fetched data in __load_pointer() __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 Signed-off-by: David S. Miller --- net/core/filter.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index e193e29d467..e8a6ac411ff 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -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); } } -- 2.41.0