From: Jakub Kicinski <kuba@kernel.org>
To: Mingyu Wang <25181214217@stu.xidian.edu.cn>
Cc: willemdebruijn.kernel@gmail.com, davem@davemloft.net,
dsahern@kernel.org, edumazet@google.com, pabeni@redhat.com,
horms@kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ipv6: udp: fix memory leak in udpv6_sendmsg error path
Date: Wed, 22 Apr 2026 08:04:33 -0700 [thread overview]
Message-ID: <20260422080433.0e5a3b47@kernel.org> (raw)
In-Reply-To: <20260422105802.486216-1-25181214217@stu.xidian.edu.cn>
On Wed, 22 Apr 2026 18:58:02 +0800 Mingyu Wang wrote:
> During fuzzing with failslab enabled, a memory leak was observed in the
> IPv6 UDP send path.
>
> When sending via the lockless fast path (!corkreq), udpv6_sendmsg()
> calls ip6_make_skb() and assumes that the routing entry (dst_entry)
> reference has been stolen by the callee. However, if ip6_make_skb()
> fails early (e.g., due to an ENOMEM from memory allocation failure),
> it returns an error pointer without consuming the dst reference.
>
> Since udpv6_sendmsg() unconditionally jumps to the 'out_no_dst' label,
> the unconsumed dst_entry is never released, resulting in a memory leak.
>
> Fix this by explicitly calling dst_release(dst) when ip6_make_skb()
> returns an error.
Test this with cmsg_ip.sh on a debug-enabled kernel before you repost.
I think it causes crashes there.
--
pw-bot: cr
next prev parent reply other threads:[~2026-04-22 15:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 10:58 [PATCH] ipv6: udp: fix memory leak in udpv6_sendmsg error path Mingyu Wang
2026-04-22 11:55 ` Sabrina Dubroca
2026-04-22 15:04 ` Jakub Kicinski [this message]
2026-04-22 15:41 ` [syzbot ci] " syzbot ci
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