From: David Laight <david.laight.linux@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Mashiro Chen <mashiro.chen@mailbox.org>,
netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com,
pabeni@redhat.com, horms@kernel.org, jreuter@yaina.de,
linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH v2 net] net: ax25: fix integer overflow in ax25_rx_fragment()
Date: Sun, 12 Apr 2026 22:05:50 +0100 [thread overview]
Message-ID: <20260412220550.0f35f5ef@pumpkin> (raw)
In-Reply-To: <20260412131751.0e90a053@kernel.org>
On Sun, 12 Apr 2026 13:17:51 -0700
Jakub Kicinski <kuba@kernel.org> wrote:
> On Thu, 9 Apr 2026 10:50:26 +0800 Mashiro Chen wrote:
> > Fix mirrors the identical bug fixed in NET/ROM (nr_in.c): check for
> > overflow before adding skb->len to fraglen, and abort fragment
> > reassembly cleanly if the limit would be exceeded.
>
> Same problem as reported by Simon on the netrom patch applies here.
>
> nit: I don't think you need to cast ax25->fraglen to unsigned int
> in the comparison. since it's added with skb->len it should get
> auto-prompted to unsigned int.
It wouldn't matter if that comparison were signed.
Or change the type of ax25->fraglen to be 32bits and do the
sanity check for overlong packets later in the code.
I had a quick look at the header and the structure hasn't
been size-optimised...
David
next prev parent reply other threads:[~2026-04-12 21:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-09 2:50 [PATCH v2 net] net: ax25: fix integer overflow in ax25_rx_fragment() Mashiro Chen
2026-04-12 20:17 ` Jakub Kicinski
2026-04-12 21:05 ` David Laight [this message]
2026-04-13 11:21 ` Mashiro Chen
2026-04-13 11:14 ` [PATCH v3 " Mashiro Chen
2026-04-13 20:49 ` [PATCH v4 " Mashiro Chen
2026-04-21 7:29 ` Paolo Abeni
2026-04-21 8:45 ` Hugh Blemings
2026-04-21 12:25 ` Andrew Lunn
2026-04-21 14:16 ` Jakub Kicinski
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