CVE-2026-43464

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ<br /> <br /> XDP multi-buf programs can modify the layout of the XDP buffer when the<br /> program calls bpf_xdp_pull_data() or bpf_xdp_adjust_tail(). The<br /> referenced commit in the fixes tag corrected the assumption in the mlx5<br /> driver that the XDP buffer layout doesn&amp;#39;t change during a program<br /> execution. However, this fix introduced another issue: the dropped<br /> fragments still need to be counted on the driver side to avoid page<br /> fragment reference counting issues.<br /> <br /> Such issue can be observed with the<br /> test_xdp_native_adjst_tail_shrnk_data selftest when using a payload of<br /> 3600 and shrinking by 256 bytes (an upcoming selftest patch): the last<br /> fragment gets released by the XDP code but doesn&amp;#39;t get tracked by the<br /> driver. This results in a negative pp_ref_count during page release and<br /> the following splat:<br /> <br /> WARNING: include/net/page_pool/helpers.h:297 at mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core], CPU#12: ip/3137<br /> Modules linked in: [...]<br /> CPU: 12 UID: 0 PID: 3137 Comm: ip Not tainted 6.19.0-rc3+ #12 NONE<br /> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014<br /> RIP: 0010:mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core]<br /> [...]<br /> Call Trace:<br /> <br /> mlx5e_dealloc_rx_wqe+0xcb/0x1a0 [mlx5_core]<br /> mlx5e_free_rx_descs+0x7f/0x110 [mlx5_core]<br /> mlx5e_close_rq+0x50/0x60 [mlx5_core]<br /> mlx5e_close_queues+0x36/0x2c0 [mlx5_core]<br /> mlx5e_close_channel+0x1c/0x50 [mlx5_core]<br /> mlx5e_close_channels+0x45/0x80 [mlx5_core]<br /> mlx5e_safe_switch_params+0x1a5/0x230 [mlx5_core]<br /> mlx5e_change_mtu+0xf3/0x2f0 [mlx5_core]<br /> netif_set_mtu_ext+0xf1/0x230<br /> do_setlink.isra.0+0x219/0x1180<br /> rtnl_newlink+0x79f/0xb60<br /> rtnetlink_rcv_msg+0x213/0x3a0<br /> netlink_rcv_skb+0x48/0xf0<br /> netlink_unicast+0x24a/0x350<br /> netlink_sendmsg+0x1ee/0x410<br /> __sock_sendmsg+0x38/0x60<br /> ____sys_sendmsg+0x232/0x280<br /> ___sys_sendmsg+0x78/0xb0<br /> __sys_sendmsg+0x5f/0xb0<br /> [...]<br /> do_syscall_64+0x57/0xc50<br /> <br /> This patch fixes the issue by doing page frag counting on all the<br /> original XDP buffer fragments for all relevant XDP actions (XDP_TX ,<br /> XDP_REDIRECT and XDP_PASS). This is basically reverting to the original<br /> counting before the commit in the fixes tag.<br /> <br /> As frag_page is still pointing to the original tail, the nr_frags<br /> parameter to xdp_update_skb_frags_info() needs to be calculated<br /> in a different way to reflect the new nr_frags.