[PATCH] net: Fix potential out of bound write in skb_try_coalesce()

From: linmiaohe
Date: Tue Aug 04 2020 - 07:46:02 EST


From: Miaohe Lin <linmiaohe@xxxxxxxxxx>

The head_frag of skb would occupy one extra skb_frag_t. Take it into
account or out of bound write to skb frags may happen.

Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
net/core/skbuff.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 8a0c39e4ab0a..b489ba201fac 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5154,7 +5154,7 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
unsigned int offset;

if (to_shinfo->nr_frags +
- from_shinfo->nr_frags >= MAX_SKB_FRAGS)
+ from_shinfo->nr_frags + 1 >= MAX_SKB_FRAGS)
return false;

if (skb_head_is_locked(from))
--
2.19.1