[PATCH net-next 4/4] net: remove two BUG() from skb_checksum_help()

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

I have a syzbot report that managed to get a crash in skb_checksum_help()

If syzbot can trigger these BUG(), it makes sense to replace
them with more friendly WARN_ON_ONCE() since skb_checksum_help()
can instead return an error code.

Note that syzbot will still crash there, until real bug is fixed.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/dev.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index f036ccb61da4da3ffc52c4f2402427054b831e8a..e12f8310dd86b312092c5d8fd50fa2ab60fce310 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3265,11 +3265,15 @@ int skb_checksum_help(struct sk_buff *skb)
 	}
 
 	offset = skb_checksum_start_offset(skb);
-	BUG_ON(offset >= skb_headlen(skb));
+	ret = -EINVAL;
+	if (WARN_ON_ONCE(offset >= skb_headlen(skb)))
+		goto out;
+
 	csum = skb_checksum(skb, offset, skb->len - offset, 0);
 
 	offset += skb->csum_offset;
-	BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));
+	if (WARN_ON_ONCE(offset + sizeof(__sum16) > skb_headlen(skb)))
+		goto out;
 
 	ret = skb_ensure_writable(skb, offset + sizeof(__sum16));
 	if (ret)
-- 
2.36.0.512.ge40c2bad7a-goog