linux-cve-announce - CVE-2025-39793: io_uring/memmap: cast nr_pages to size

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025091223-CVE-2025-39793-9d74@gregkh>
Date: Fri, 12 Sep 2025 17:59:23 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39793: io_uring/memmap: cast nr_pages to size_t before shifting

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

io_uring/memmap: cast nr_pages to size_t before shifting

If the allocated size exceeds UINT_MAX, then it's necessary to cast
the mr->nr_pages value to size_t to prevent it from overflowing. In
practice this isn't much of a concern as the required memory size will
have been validated upfront, and accounted to the user. And > 4GB sizes
will be necessary to make the lack of a cast a problem, which greatly
exceeds normal user locked_vm settings that are generally in the kb to
mb range. However, if root is used, then accounting isn't done, and
then it's possible to hit this issue.

The Linux kernel CVE team has assigned CVE-2025-39793 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.14 with commit 087f997870a948820ec366701d178f402c6a23a3 and fixed in 6.15.11 with commit c6a2706e08b8a1b2d3740161c0977d38e596c1ee
	Issue introduced in 6.14 with commit 087f997870a948820ec366701d178f402c6a23a3 and fixed in 6.16.2 with commit a69a9b53c54e2d33e2a5b1ea4a9a71fd01c6cf3a
	Issue introduced in 6.14 with commit 087f997870a948820ec366701d178f402c6a23a3 and fixed in 6.17-rc1 with commit 33503c083fda048c77903460ac0429e1e2c0e341

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-2025-39793
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/memmap.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/c6a2706e08b8a1b2d3740161c0977d38e596c1ee
	https://git.kernel.org/stable/c/a69a9b53c54e2d33e2a5b1ea4a9a71fd01c6cf3a
	https://git.kernel.org/stable/c/33503c083fda048c77903460ac0429e1e2c0e341