CVE-2026-43465

Estado: AnalizadaCrítica (9.8)—

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

net/mlx5e: RX, Fix XDP multi-buf frag counting for striding 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.

Resulting splat during the test:

Leer descripción completaMostrar menos

The problem applies for XDP_PASS as well which is handled in a different code path in the driver.

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.

Detalles técnicos trazas, registros y código del informe original

The issue was discovered by the drivers/net/xdp.py selftest,
more specifically the test_xdp_native_tx_mb:
- The mlx5 driver allocates a page_pool page and initializes it with
  a frag counter of 64 (pp_ref_count=64) and the internal frag counter
  to 0.
- The test sends one packet with no payload.
- On RX (mlx5e_skb_from_cqe_mpwrq_nonlinear()), mlx5 configures the XDP
  buffer with the packet data starting in the first fragment which is the
  page mentioned above.
- The XDP program runs and calls bpf_xdp_pull_data() which moves the
  header into the linear part of the XDP buffer. As the packet doesn't
  contain more data, the program drops the tail fragment since it no
  longer contains any payload (pp_ref_count=63).
- mlx5 device skips counting this fragment. Internal frag counter
  remains 0.
- mlx5 releases all 64 fragments of the page but page pp_ref_count is
  63 => negative reference counting error.

  WARNING: CPU: 0 PID: 188225 at ./include/net/page_pool/helpers.h:297 mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core]
  Modules linked in: [...]
  CPU: 0 UID: 0 PID: 188225 Comm: ip Not tainted 6.18.0-rc7_for_upstream_min_debug_2025_12_08_11_44 #1 NONE
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core]
  [...]
  Call Trace:
   <TASK>
   mlx5e_free_rx_mpwqe+0x20a/0x250 [mlx5_core]
   mlx5e_dealloc_rx_mpwqe+0x37/0xb0 [mlx5_core]
   mlx5e_free_rx_descs+0x11a/0x170 [mlx5_core]
   mlx5e_close_rq+0x78/0xa0 [mlx5_core]
   mlx5e_close_queues+0x46/0x2a0 [mlx5_core]
   mlx5e_close_channel+0x24/0x90 [mlx5_core]
   mlx5e_close_channels+0x5d/0xf0 [mlx5_core]
   mlx5e_safe_switch_params+0x2ec/0x380 [mlx5_core]
   mlx5e_change_mtu+0x11d/0x490 [mlx5_core]
   mlx5e_change_nic_mtu+0x19/0x30 [mlx5_core]
   netif_set_mtu_ext+0xfc/0x240
   do_setlink.isra.0+0x226/0x1100
   rtnl_newlink+0x7a9/0xba0
   rtnetlink_rcv_msg+0x220/0x3c0
   netlink_rcv_skb+0x4b/0xf0
   netlink_unicast+0x255/0x380
   netlink_sendmsg+0x1f3/0x420
   __sock_sendmsg+0x38/0x60
   ____sys_sendmsg+0x1e8/0x240
   ___sys_sendmsg+0x7c/0xb0
   [...]
   __sys_sendmsg+0x5f/0xb0
   do_syscall_64+0x55/0xc70

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.78%
Percentil entre todas las CVEs puntuadas: 54
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access45 %
Impacto principalT1499.004 Application or System Exploitationimpact50 %
Impacto secundarioT1561.001 Disk Content Wipeimpact35 %

Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N indica vulnerabilidad remota sin autenticación, pero el contexto describe un defecto en lógica de conteo de fragmentos de páginas en XDP del kernel, no una explotación de red directa. El impacto primario es DoS por exhaustión de recursos (reference counting error

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

NVD-CWE-Other

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ\n\nXDP multi-buf programs can modify the layout of the XDP buffer when the\nprogram calls bpf_xdp_pull_data() or bpf_xdp_adjust_tail(). The\nreferenced commit in the fixes tag corrected the assumption in the mlx5\ndriver that the XDP buffer layout doesn't change during a program\nexecution. However, this fix introduced another issue: the dropped\nfragments still need to be counted on the driver side to avoid page\nfragment reference counting issues.\n\nThe issue was discovered by the drivers/net/xdp.py selftest,\nmore specifically the test_xdp_native_tx_mb:\n- The mlx5 driver allocates a page_pool page and initializes it with\n  a frag counter of 64 (pp_ref_count=64) and the internal frag counter\n  to 0.\n- The test sends one packet with no payload.\n- On RX (mlx5e_skb_from_cqe_mpwrq_nonlinear()), mlx5 configures the XDP\n  buffer with the packet data starting in the first fragment which is the\n  page mentioned above.\n- The XDP program runs and calls bpf_xdp_pull_data() which moves the\n  header into the linear part of the XDP buffer. As the packet doesn't\n  contain more data, the program drops the tail fragment since it no\n  longer contains any payload (pp_ref_count=63).\n- mlx5 device skips counting this fragment. Internal frag counter\n  remains 0.\n- mlx5 releases all 64 fragments of the page but page pp_ref_count is\n  63 => negative reference counting error.\n\nResulting splat during the test:\n\n  WARNING: CPU: 0 PID: 188225 at ./include/net/page_pool/helpers.h:297 mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core]\n  Modules linked in: [...]\n  CPU: 0 UID: 0 PID: 188225 Comm: ip Not tainted 6.18.0-rc7_for_upstream_min_debug_2025_12_08_11_44 #1 NONE\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014\n  RIP: 0010:mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core]\n  [...]\n  Call Trace:\n   <TASK>\n   mlx5e_free_rx_mpwqe+0x20a/0x250 [mlx5_core]\n   mlx5e_dealloc_rx_mpwqe+0x37/0xb0 [mlx5_core]\n   mlx5e_free_rx_descs+0x11a/0x170 [mlx5_core]\n   mlx5e_close_rq+0x78/0xa0 [mlx5_core]\n   mlx5e_close_queues+0x46/0x2a0 [mlx5_core]\n   mlx5e_close_channel+0x24/0x90 [mlx5_core]\n   mlx5e_close_channels+0x5d/0xf0 [mlx5_core]\n   mlx5e_safe_switch_params+0x2ec/0x380 [mlx5_core]\n   mlx5e_change_mtu+0x11d/0x490 [mlx5_core]\n   mlx5e_change_nic_mtu+0x19/0x30 [mlx5_core]\n   netif_set_mtu_ext+0xfc/0x240\n   do_setlink.isra.0+0x226/0x1100\n   rtnl_newlink+0x7a9/0xba0\n   rtnetlink_rcv_msg+0x220/0x3c0\n   netlink_rcv_skb+0x4b/0xf0\n   netlink_unicast+0x255/0x380\n   netlink_sendmsg+0x1f3/0x420\n   __sock_sendmsg+0x38/0x60\n   ____sys_sendmsg+0x1e8/0x240\n   ___sys_sendmsg+0x7c/0xb0\n   [...]\n   __sys_sendmsg+0x5f/0xb0\n   do_syscall_64+0x55/0xc70\n\nThe problem applies for XDP_PASS as well which is handled in a different\ncode path in the driver.\n\nThis patch fixes the issue by doing page frag counting on all the\noriginal XDP buffer fragments for all relevant XDP actions (XDP_TX ,\nXDP_REDIRECT and XDP_PASS). This is basically reverting to the original\ncounting before the commit in the fixes tag.\n\nAs frag_page is still pointing to the original tail, the nr_frags\nparameter to xdp_update_skb_frags_info() needs to be calculated\nin a different way to reflect the new nr_frags."
    }
  ],
  "lastModified": "2026-06-17T10:49:39.167",
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