netdev - Re: [PATCH net] atm: null pointer dereference when both entry and holding

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Message-ID: <20250319120320.GA280585@kernel.org>
Date: Wed, 19 Mar 2025 12:03:20 +0000
From: Simon Horman <horms@...nel.org>
To: pwn9uin@...il.com
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, Minjoong Kim <alswnd4123@...look.kr>
Subject: Re: [PATCH net] atm: null pointer dereference when both entry and
 holding_time are  NULL.

On Fri, Mar 14, 2025 at 12:34:04AM +0000, pwn9uin@...il.com wrote:
> From: Minjoong Kim <alswnd4123@...look.kr>
> 
> When MPOA_cache_impos_rcvd() receives the msg, it can trigger
> Null Pointer Dereference Vulnerability if both entry and
> holding_time are NULL. Because there is only for the situation
> where entry is NULL and holding_time exists, it can be passed
> when both entry and holding_time are NULL. If these are NULL,
> the entry will be passd to eg_cache_put() as parameter and
> it is referenced by entry->use code in it.
> 
> Signed-off-by: Minjoong Kim <alswnd4123@...look.kr>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")

Hi,

I agree this is a theoretical possibility, but can it occur in practice?
Have you observed this problem? I think some analysis of that is warranted.

Also, Smatch tells me that there is a potential dereference of mpc while
NULL. Perhaps you could look at making a patch for that too?