{"id":"CVE-2026-64210","summary":"net/mlx5e: xsk: Fix unlocked writing to ICOSQ","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: xsk: Fix unlocked writing to ICOSQ\n\nDuring napi poll, when the affinity changes and there's still XSK work\nto be done, we trigger an ICOSQ interrupt on the new CPU. However, this\ntriggering on the ICOSQ is done unprotected.\n\nThere are 2 such races:\n\nA) mlx5e_trigger_irq() is called while mlx5e_xsk_alloc_rx_mpwqe() is\nrunning from a different CPU due to affinity change. This can happen\nbecause IRQ triggering is done after napi_complete_done(). At this point\nthe NAPI can be scheduled on a different CPU. Like this:\n\n  CPU A (old affinity, NAPI tail)    CPU B (new affinity, fresh NAPI)\n  -------------------------------    --------------------------------\n  napi_complete_done()  clears SCHED\n  mlx5e_cq_arm(...)\n                                     napi_schedule_prep() sets SCHED\n                                     mlx5e_napi_poll()\n                                       mlx5e_xsk_alloc_rx_mpwqe()\n                                         mlx5e_icosq_sync_lock() // noop\n                                         memcpy 640 B UMR body\n                                         advance sq-\u003epc by 10\n  mlx5e_trigger_irq(&c-\u003eicosq)\n    wqe_info[pi] = {NOP, 1}\n    mlx5e_post_nop() advances sq-\u003epc\n\nB) mlx5e_trigger_irq() is called on the ICOSQ when\nmlx5e_trigger_napi_icosq() is running.\n\nThe obvious fix would be to lock the ICOSQ. But ICOSQ has an optimized\nlocking scheme that doesn't work for this scenario. Kick the async ICOSQ\ninstead which is always locked.\n\nThis issue was noticed in the wild with the following splat:\n\n  netdevice: ge-0-0-1: Bad OP in ICOSQ CQE: 0xd\n  WARNING: drivers/net/ethernet/mellanox/mlx5/core/en_rx.c:826 [...]\n  [...]\n  Call Trace:\n   \u003cIRQ\u003e\n   mlx5e_napi_poll+0x11d/0x7f0 [mlx5_core]\n   __napi_poll+0x30/0x200\n   ? skb_defer_free_flush+0x9c/0xc0\n   net_rx_action+0x2fe/0x3f0\n   handle_softirqs+0xd8/0x340\n   __irq_exit_rcu+0xbc/0xe0\n   common_interrupt+0x85/0xa0\n   \u003c/IRQ\u003e\n   \u003cTASK\u003e\n   asm_common_interrupt+0x26/0x40\n  [...]\n  ---[ end trace 0000000000000000 ]---\n  mlx5_core 0000:08:00.0 ge-0-0-1: Error cqe on cqn 0x548, ci 0x2022, qn 0x8f4,\n  opcode 0xd, syndrome 0x2, vendor syndrome 0x68\n  00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n  00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n  00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n  00000030: 00 00 00 00 01 00 68 02 01 00 08 f4 de 14 59 d2\n  WQE DUMP: WQ size 16384 WQ cur size 0, WQE index 0x1e14, len: 64\n  00000000: 00 00 00 01 d9 ed 80 02 00 00 00 01 d9 ed 90 02\n  00000010: 00 00 00 01 d9 ed a0 02 00 00 00 01 d9 ed b0 02\n  00000020: 00 00 00 01 d9 ed c0 02 00 00 00 01 d9 ed d0 02\n  00000030: 00 00 00 01 d9 ed e0 02 00 00 00 01 d9 ed f0 02\n  mlx5_core 0000:08:00.0 ge-0-0-1: Error cqe on cqn 0x548, ci 0x2023, qn 0x8f4,\n  opcode 0xd, syndrome 0x5, vendor syndrome 0xf9\n  00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n  00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n  00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n  00000030: 00 00 00 00 01 00 f9 05 01 00 08 f4 de 15 cf d2","modified":"2026-07-28T03:46:32.947291410Z","published":"2026-07-24T15:23:01.328Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64210.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/8d3b91e7d81000d295cd914d4d9d6f860252e2bf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c326f9c68921e2f14dfcecb2f6b4216313d50248"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64210.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64210"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"db05815b36cbd486c86fd002dfa81c9af6245e25"},{"fixed":"8d3b91e7d81000d295cd914d4d9d6f860252e2bf"},{"fixed":"c326f9c68921e2f14dfcecb2f6b4216313d50248"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64210.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.3.0"},{"fixed":"7.0.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64210.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}