From 78a0cb2f45dc9327f26956c242f7f4b450efff49 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 5 Nov 2024 17:44:00 +0000 Subject: [PATCH] net: add debug check in skb_reset_inner_mac_header() Make sure (skb->data - skb->head) can fit in skb->inner_mac_header This needs CONFIG_DEBUG_NET=y. Signed-off-by: Eric Dumazet Reviewed-by: Joe Damato Reviewed-by: Xuan Zhuo Link: https://patch.msgid.link/20241105174403.850330-5-edumazet@google.com Signed-off-by: Jakub Kicinski --- include/linux/skbuff.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 8dafd1295a6e..32a7d8a65b9f 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2982,7 +2982,10 @@ static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb) static inline void skb_reset_inner_mac_header(struct sk_buff *skb) { - skb->inner_mac_header = skb->data - skb->head; + long offset = skb->data - skb->head; + + DEBUG_NET_WARN_ON_ONCE(offset != (typeof(skb->inner_mac_header))offset); + skb->inner_mac_header = offset; } static inline void skb_set_inner_mac_header(struct sk_buff *skb, -- 2.25.1