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Message-ID: <2b8f2e56-15be-4732-baf5-7a3df4f8a1fe@gmail.com>
Date: Mon, 4 May 2026 07:02:30 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Mohamed salem Eddah <medsalemeddah@...il.com>, security@...nel.org,
 oss-security@...ts.openwall.com, "axboe@...nel.dk" <axboe@...nel.dk>
Subject: Re: CVE request: io_uring zcrx freelist OOB write

On 5/3/26 12:00, Mohamed salem Eddah wrote:
> Hello,
> 
> I am reporting a security issue in the Linux kernel involving an
> out-of-bounds heap write in io_uring/zcrx.c.
> 
> This issue appears to have been addressed in commit 770594e
> (“io_uring/zcrx: warn on freelist violations”, April 21, 2026), however it
> was not assigned a CVE and does not appear to have been included in a
> formal security advisory. As a result, multiple stable and downstream
> distribution kernels are still affected.
> ------------------------------
> Vulnerability Summary
> 
> *File:* io_uring/zcrx.c
> *Function:* io_zcrx_return_niov_freelist()
> *Introduced:* Linux 6.12 (initial ZCRX merge)

FWIW, it was added IIRC in 6.15, but not 6.12

> *Fixed upstream:* 770594e (Apr 21, 2026)
> *Status:* Fix not yet present in stable releases
Did you trigger the problem or the warning in a new kernel
without the attached modules? Which kernel version / hash
was it? There was a fix for the scrub case, but otherwise
don't immediately see how that can happen. I'll take a look.

-- 
Pavel Begunkov

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