CVE-2026-23294

{"id": "CVE-2026-23294", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.0, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 1.0}]}, "published": "2026-03-25T11:16:24.697", "references": [{"url": "https://git.kernel.org/stable/c/1872e75375c40add4a35990de3be77b5741c252c", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/6c10b019785dc282c5f45d21e4a3f468b8fd6476", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/ab1a56c9d99189aa5c6e03940d06e40ba6a28240", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-362"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix race in devmap on PREEMPT_RT\n\nOn PREEMPT_RT kernels, the per-CPU xdp_dev_bulk_queue (bq) can be\naccessed concurrently by multiple preemptible tasks on the same CPU.\n\nThe original code assumes bq_enqueue() and __dev_flush() run atomically\nwith respect to each other on the same CPU, relying on\nlocal_bh_disable() to prevent preemption. However, on PREEMPT_RT,\nlocal_bh_disable() only calls migrate_disable() (when\nPREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable\npreemption, which allows CFS scheduling to preempt a task during\nbq_xmit_all(), enabling another task on the same CPU to enter\nbq_enqueue() and operate on the same per-CPU bq concurrently.\n\nThis leads to several races:\n\n1. Double-free / use-after-free on bq->q[]: bq_xmit_all() snapshots\n cnt = bq->count, then iterates bq->q[0..cnt-1] to transmit frames.\n If preempted after the snapshot, a second task can call bq_enqueue()\n -> bq_xmit_all() on the same bq, transmitting (and freeing) the\n same frames. When the first task resumes, it operates on stale\n pointers in bq->q[], causing use-after-free.\n\n2. bq->count and bq->q[] corruption: concurrent bq_enqueue() modifying\n bq->count and bq->q[] while bq_xmit_all() is reading them.\n\n3. dev_rx/xdp_prog teardown race: __dev_flush() clears bq->dev_rx and\n bq->xdp_prog after bq_xmit_all(). If preempted between\n bq_xmit_all() return and bq->dev_rx = NULL, a preempting\n bq_enqueue() sees dev_rx still set (non-NULL), skips adding bq to\n the flush_list, and enqueues a frame. When __dev_flush() resumes,\n it clears dev_rx and removes bq from the flush_list, orphaning the\n newly enqueued frame.\n\n4. __list_del_clearprev() on flush_node: similar to the cpumap race,\n both tasks can call __list_del_clearprev() on the same flush_node,\n the second dereferences the prev pointer already set to NULL.\n\nThe race between task A (__dev_flush -> bq_xmit_all) and task B\n(bq_enqueue -> bq_xmit_all) on the same CPU:\n\n Task A (xdp_do_flush) Task B (ndo_xdp_xmit redirect)\n ---------------------- --------------------------------\n __dev_flush(flush_list)\n bq_xmit_all(bq)\n cnt = bq->count /* e.g. 16 */\n /* start iterating bq->q[] */\n <-- CFS preempts Task A -->\n bq_enqueue(dev, xdpf)\n bq->count == DEV_MAP_BULK_SIZE\n bq_xmit_all(bq, 0)\n cnt = bq->count /* same 16! */\n ndo_xdp_xmit(bq->q[])\n /* frames freed by driver */\n bq->count = 0\n <-- Task A resumes -->\n ndo_xdp_xmit(bq->q[])\n /* use-after-free: frames already freed! */\n\nFix this by adding a local_lock_t to xdp_dev_bulk_queue and acquiring\nit in bq_enqueue() and __dev_flush(). These paths already run under\nlocal_bh_disable(), so use local_lock_nested_bh() which on non-RT is\na pure annotation with no overhead, and on PREEMPT_RT provides a\nper-CPU sleeping lock that serializes access to the bq."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nbpf: Corrige condici\u00f3n de carrera en devmap en PREEMPT_RT\n\nEn kernels PREEMPT_RT, la xdp_dev_bulk_queue (bq) por CPU puede ser accedida concurrentemente por m\u00faltiples tareas preemptivas en la misma CPU.\n\nEl c\u00f3digo original asume que bq_enqueue() y __dev_flush() se ejecutan at\u00f3micamente con respecto la una a la otra en la misma CPU, confiando en local_bh_disable() para prevenir la expropiaci\u00f3n. Sin embargo, en PREEMPT_RT, local_bh_disable() solo llama a migrate_disable() (cuando PREEMPT_RT_NEEDS_BH_LOCK no est\u00e1 configurado) y no deshabilita la expropiaci\u00f3n, lo que permite que la planificaci\u00f3n CFS expropie una tarea durante bq_xmit_all(), permitiendo que otra tarea en la misma CPU entre en bq_enqueue() y opere en la misma bq por CPU concurrentemente.\n\nEsto lleva a varias condiciones de carrera:\n\n1. Doble liberaci\u00f3n / uso despu\u00e9s de liberaci\u00f3n en bq-&gt;q[]: bq_xmit_all() toma una instant\u00e1nea de cnt = bq-&gt;count, luego itera bq-&gt;q[0..cnt-1] para transmitir tramas. Si es expropiada despu\u00e9s de la instant\u00e1nea, una segunda tarea puede llamar a bq_enqueue() -&gt; bq_xmit_all() en la misma bq, transmitiendo (y liberando) las mismas tramas. Cuando la primera tarea se reanuda, opera con punteros obsoletos en bq-&gt;q[], causando uso despu\u00e9s de liberaci\u00f3n.\n\n2. Corrupci\u00f3n de bq-&gt;count y bq-&gt;q[]: bq_enqueue() concurrente modificando bq-&gt;count y bq-&gt;q[] mientras bq_xmit_all() los est\u00e1 leyendo.\n\n3. Condici\u00f3n de carrera de desmontaje de dev_rx/xdp_prog: __dev_flush() borra bq-&gt;dev_rx y bq-&gt;xdp_prog despu\u00e9s de bq_xmit_all(). Si es expropiada entre el retorno de bq_xmit_all() y bq-&gt;dev_rx = NULL, una bq_enqueue() expropiadora ve dev_rx a\u00fan configurado (no-NULL), omite a\u00f1adir bq a la flush_list, y encola una trama. Cuando __dev_flush() se reanuda, borra dev_rx y elimina bq de la flush_list, dejando hu\u00e9rfana la trama reci\u00e9n encolada.\n\n4. __list_del_clearprev() en flush_node: similar a la condici\u00f3n de carrera de cpumap, ambas tareas pueden llamar a __list_del_clearprev() en el mismo flush_node, la segunda desreferencia el puntero prev ya establecido en NULL.\n\nLa condici\u00f3n de carrera entre la tarea A (__dev_flush -&gt; bq_xmit_all) y la tarea B (bq_enqueue -&gt; bq_xmit_all) en la misma CPU:\n\n Tarea A (xdp_do_flush) Tarea B (redirecci\u00f3n ndo_xdp_xmit)\n ---------------------- --------------------------------\n __dev_flush(flush_list)\n bq_xmit_all(bq)\n cnt = bq-&gt;count /* ej. 16 */\n /* comienza a iterar bq-&gt;q[] */\n &lt;-- CFS expropia la Tarea A --&gt;\n bq_enqueue(dev, xdpf)\n bq-&gt;count == DEV_MAP_BULK_SIZE\n bq_xmit_all(bq, 0)\n cnt = bq-&gt;count /* \u00a1los mismos 16! */\n ndo_xdp_xmit(bq-&gt;q[])\n /* tramas liberadas por el controlador */\n bq-&gt;count = 0\n &lt;-- La Tarea A se reanuda --&gt;\n ndo_xdp_xmit(bq-&gt;q[])\n /* uso despu\u00e9s de liberaci\u00f3n: \u00a1tramas ya liberadas! */\n\nSolucione esto a\u00f1adiendo un local_lock_t a xdp_dev_bulk_queue y adquiri\u00e9ndolo en bq_enqueue() y __dev_flush(). Estas rutas ya se ejecutan bajo local_bh_disable(), as\u00ed que use local_lock_nested_bh() que en no-RT es una anotaci\u00f3n pura sin sobrecarga, y en PREEMPT_RT proporciona un bloqueo de suspensi\u00f3n por CPU que serializa el acceso a la bq."}], "lastModified": "2026-05-29T14:43:26.227", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "91D34097-62D4-400A-8894-1A45A5B44EEA", "versionEndExcluding": "6.18.17", "versionStartIncluding": "6.18"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3", "versionEndExcluding": "6.19.7", "versionStartIncluding": "6.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}