From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-43464: net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ
Date: Fri, 8 May 2026 16:23:13 +0200 [thread overview]
Message-ID: <2026050802-CVE-2026-43464-5c7a@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ
XDP multi-buf programs can modify the layout of the XDP buffer when the
program calls bpf_xdp_pull_data() or bpf_xdp_adjust_tail(). The
referenced commit in the fixes tag corrected the assumption in the mlx5
driver that the XDP buffer layout doesn't change during a program
execution. However, this fix introduced another issue: the dropped
fragments still need to be counted on the driver side to avoid page
fragment reference counting issues.
Such issue can be observed with the
test_xdp_native_adjst_tail_shrnk_data selftest when using a payload of
3600 and shrinking by 256 bytes (an upcoming selftest patch): the last
fragment gets released by the XDP code but doesn't get tracked by the
driver. This results in a negative pp_ref_count during page release and
the following splat:
WARNING: include/net/page_pool/helpers.h:297 at mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core], CPU#12: ip/3137
Modules linked in: [...]
CPU: 12 UID: 0 PID: 3137 Comm: ip Not tainted 6.19.0-rc3+ #12 NONE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
RIP: 0010:mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core]
[...]
Call Trace:
<TASK>
mlx5e_dealloc_rx_wqe+0xcb/0x1a0 [mlx5_core]
mlx5e_free_rx_descs+0x7f/0x110 [mlx5_core]
mlx5e_close_rq+0x50/0x60 [mlx5_core]
mlx5e_close_queues+0x36/0x2c0 [mlx5_core]
mlx5e_close_channel+0x1c/0x50 [mlx5_core]
mlx5e_close_channels+0x45/0x80 [mlx5_core]
mlx5e_safe_switch_params+0x1a5/0x230 [mlx5_core]
mlx5e_change_mtu+0xf3/0x2f0 [mlx5_core]
netif_set_mtu_ext+0xf1/0x230
do_setlink.isra.0+0x219/0x1180
rtnl_newlink+0x79f/0xb60
rtnetlink_rcv_msg+0x213/0x3a0
netlink_rcv_skb+0x48/0xf0
netlink_unicast+0x24a/0x350
netlink_sendmsg+0x1ee/0x410
__sock_sendmsg+0x38/0x60
____sys_sendmsg+0x232/0x280
___sys_sendmsg+0x78/0xb0
__sys_sendmsg+0x5f/0xb0
[...]
do_syscall_64+0x57/0xc50
This patch fixes the issue by doing page frag counting on all the
original XDP buffer fragments for all relevant XDP actions (XDP_TX ,
XDP_REDIRECT and XDP_PASS). This is basically reverting to the original
counting before the commit in the fixes tag.
As frag_page is still pointing to the original tail, the nr_frags
parameter to xdp_update_skb_frags_info() needs to be calculated
in a different way to reflect the new nr_frags.
The Linux kernel CVE team has assigned CVE-2026-43464 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.18 with commit afd5ba577c10639f62e8120df67dc70ea4b61176 and fixed in 6.18.19 with commit c74557495efb4bd0adefdfc8678ecdbc82a06da3
Issue introduced in 6.18 with commit afd5ba577c10639f62e8120df67dc70ea4b61176 and fixed in 6.19.9 with commit 03cb50e5b74fce8bf6d92b860371b66253cf0f8d
Issue introduced in 6.18 with commit afd5ba577c10639f62e8120df67dc70ea4b61176 and fixed in 7.0 with commit a6413e6f6c9d9bb9833324cb3753582f7bc0f2fa
Issue introduced in 6.6.115 with commit 72328f25755ee966724f46e3a0e8e59bef2091ba
Issue introduced in 6.12.56 with commit 0049fd63881505566824e88cfa624638f921c808
Issue introduced in 6.17.6 with commit d969645b9b7810289bf3c353ea06957373756b8e
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-2026-43464
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:
drivers/net/ethernet/mellanox/mlx5/core/en_rx.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/c74557495efb4bd0adefdfc8678ecdbc82a06da3
https://git.kernel.org/stable/c/03cb50e5b74fce8bf6d92b860371b66253cf0f8d
https://git.kernel.org/stable/c/a6413e6f6c9d9bb9833324cb3753582f7bc0f2fa
reply other threads:[~2026-05-08 14:26 UTC|newest]
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