From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-81009: io_uring/query: cap user size passed to copy_struct_to_user
Date: Fri, 11 Sep 2026 21:41:55 +0200 [thread overview]
Message-ID: <2026091153-CVE-2026-81009-bc08@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
io_uring/query: cap user size passed to copy_struct_to_user
io_handle_query_entry() clamps hdr.size for the inbound copy_from_user()
but keeps the original user value as usize. copy_struct_to_user() uses
that usize and, when it is larger than the kernel result, clear_user()s
the trailing bytes.
As hdr.size is a __u32, a query can request nearly 4 GiB of zeroing,
including on the error path where res_size stays 0. The interface is
reachable without a ring via IORING_REGISTER_QUERY.
Reject sizes larger than PAGE_SIZE, as recommended for copy_struct_*
interfaces.
The Linux kernel CVE team has assigned CVE-2026-81009 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.18 with commit c265ae75f900cea4e415230a77b5d152377627dd and fixed in 6.18.50 with commit 417e02f7b6051765b91cf1289071882eebd172e0
Issue introduced in 6.18 with commit c265ae75f900cea4e415230a77b5d152377627dd and fixed in 7.2.4 with commit 2b8ad4981ecedb14c1fdd811ab977010b23933e6
Issue introduced in 6.18 with commit c265ae75f900cea4e415230a77b5d152377627dd and fixed in 7.3-rc1 with commit ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-81009
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
io_uring/query.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/417e02f7b6051765b91cf1289071882eebd172e0
https://git.kernel.org/stable/c/2b8ad4981ecedb14c1fdd811ab977010b23933e6
https://git.kernel.org/stable/c/ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b
reply other threads:[~2026-09-11 19:49 UTC|newest]
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