linux-kernel - Re: [Intel-wired-lan] [PATCH v2] e1000: fix OOB in e1000_tbi_should

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Message-ID: <a4ea0043-9ee1-4b9d-a2b3-811c36b12ab8@molgen.mpg.de>
Date: Tue, 2 Dec 2025 12:53:10 +0100
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Guangshuo Li <lgs201920130244@...il.com>
Cc: Jesse Brandeburg <jbrandeburg@...udflare.com>,
 Tony Nguyen <anthony.l.nguyen@...el.com>,
 "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Florian Westphal <fw@...len.de>,
 intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org,
 Tony Nguyen <tony.nguyen@...el.com>
Subject: Re: [Intel-wired-lan] [PATCH v2] e1000: fix OOB in
 e1000_tbi_should_accept()

Dear Guangshuo,


Thank you for your quick and insightful reply. (No need to resend this 
often.)

Am 02.12.25 um 12:34 schrieb Guangshuo Li:

> thanks for your comments.
> 
> ----Do you have reproducer to forth an invalid length?
> 
> Yes. The issue is reproducible with a concrete system call sequence.
> 
> I am running on top of a fuzzer called PrIntFuzz, which is built on
> syzkaller. PrIntFuzz adds a custom syscall syz_prepare_data() that is
> used to simulate device input. In other words, the device side traffic
> is not coming from a real hardware device, but is deliberately
> constructed by the fuzzer through syz_prepare_data().
> 
> The exact reproducer is provided in the attached syzkaller program
> (system call sequence) generated by PrIntFuzz, which consistently
> triggers the invalid length and the crash on my setup.
> 
> (The attached program is exactly the sequence I am running to
> reproduce the problem.)

Thank you for attaching it. Excuse my ignorance, but how do I run it?

> ----Should an error be logged, or is it a common scenario, that such
> traffic exists?
> 
> In normal deployments, I don’t expect such traffic from a well-behaved
> I2C device. In my case, the malformed length only appears because
> PrIntFuzz is intentionally crafting invalid inputs and feeding them to
> the driver via syz_prepare_data(). So this is not a “common” or
> expected scenario in real-world use, but it is a realistic
> attacker/fuzzer scenario, since the length field can be controlled by
> an external peer/device.
> 
> Given that, I think the driver should treat an invalid length as an
> error and fail the request instead of trusting it and risking memory
> corruption.
> 
> Regarding logging, I’m fully open to your preference. From my point of
> view, logging this as an error seems reasonable, because it indicates
> malformed or buggy input from the device side. However, if you expect
> this condition might occur more frequently in practice and would
> prefer to reduce noise, I can switch it to dev_dbg() or even drop the
> log entirely.
> 
> Please let me know which logging level you would prefer, and I will
> update the patch accordingly.
Then I’d suggest to add an error message with error level so people 
notice and can take a look.


Kind regards,

Paul