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Message-ID: <20231006173355.2254983-1-edumazet@google.com>
Date: Fri, 6 Oct 2023 17:33:54 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>, Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net] net: refine debug info in skb_checksum_help()
syzbot uses panic_on_warn.
This means that the skb_dump() I added in the blamed commit are
not even called.
Rewrite this so that we get the needed skb dump before syzbot crashes.
Fixes: eeee4b77dc52 ("net: add more debug info in skb_checksum_help()")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: Willem de Bruijn <willemb@...gle.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 85df22f05c38b663f050410b9f7bcd32dd781951..5aaf5753d4e46c7c4b67b00daadeda9784708dfe 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3292,15 +3292,19 @@ int skb_checksum_help(struct sk_buff *skb)
offset = skb_checksum_start_offset(skb);
ret = -EINVAL;
- if (WARN_ON_ONCE(offset >= skb_headlen(skb))) {
+ if (unlikely(offset >= skb_headlen(skb))) {
DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false);
+ WARN_ONCE(true, "offset (%d) >= skb_headlen() (%u)\n",
+ offset, skb_headlen(skb));
goto out;
}
csum = skb_checksum(skb, offset, skb->len - offset, 0);
offset += skb->csum_offset;
- if (WARN_ON_ONCE(offset + sizeof(__sum16) > skb_headlen(skb))) {
+ if (unlikely(offset + sizeof(__sum16) > skb_headlen(skb))) {
DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false);
+ WARN_ONCE(true, "offset+2 (%zu) > skb_headlen() (%u)\n",
+ offset + sizeof(__sum16), skb_headlen(skb));
goto out;
}
ret = skb_ensure_writable(skb, offset + sizeof(__sum16));
--
2.42.0.609.gbb76f46606-goog
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