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CVE-2025-39749

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <90de9c94ea72327cfa9c2c9f6113c23a513af60b, <=6.1.*, <=6.12.*, <=6.16.*, 6.17, 0, <b55947b725f190396f475d5d0c59aa855a4d8895, <=6.15.*, 5.4.297, 6.6.103, <b5de8d80b5d049f051b95d9b1ee50ae4ab656124, <f937759c7432d6151b73e1393b6517661813d506, <=5.10.*, <=6.6.*, 5.15.190, 5.3, <=5.4.*, 6.12.43, <5.3, <0ad84d62217488e679ecc90e8628980dcc003de3, 6.1.149, 6.16.2, 5.10.241, <=*, <e35e711c78c8a4c43330c0dcb1c4d507a19c20f4, <=5.15.*, <55e11f6776798b27cf09a7aa0d718415d4fc9cf5, <90c09d57caeca94e6f3f87c49e96a91edd40cbfd, <74f58f382a7c8333f8d09701aefaa25913bdbe0e, 6.15.11, 0864f057b050bc6dd68106b3185e02db5140012d

Description

In the Linux kernel, the following vulnerability has been resolved: rcu: Protect ->defer_qs_iw_pending from data race On kernels built with CONFIG_IRQ_WORK=y, when rcu_read_unlock() is invoked within an interrupts-disabled region of code [1], it will invoke rcu_read_unlock_special(), which uses an irq-work handler to force the system to notice when the RCU read-side critical section actually ends. That end won't happen until interrupts are enabled at the soonest. In some kernels, such as those booted with rcutree.use_softirq=y, the irq-work handler is used unconditionally. The per-CPU rcu_data structure's ->defer_qs_iw_pending field is updated by the irq-work handler and is both read and updated by rcu_read_unlock_special(). This resulted in the following KCSAN splat: ------------------------------------------------------------------------ BUG: KCSAN: data-race in rcu_preempt_deferred_qs_handler / rcu_read_unlock_special read to 0xffff96b95f42d8d8 of 1 bytes by task 90 on cpu 8: rcu_read_unlock_special+0x175/0x260 __rcu_read_unlock+0x92/0xa0 rt_spin_unlock+0x9b/0xc0 __local_bh_enable+0x10d/0x170 __local_bh_enable_ip+0xfb/0x150 rcu_do_batch+0x595/0xc40 rcu_cpu_kthread+0x4e9/0x830 smpboot_thread_fn+0x24d/0x3b0 kthread+0x3bd/0x410 ret_from_fork+0x35/0x40 ret_from_fork_asm+0x1a/0x30 write to 0xffff96b95f42d8d8 of 1 bytes by task 88 on cpu 8: rcu_preempt_deferred_qs_handler+0x1e/0x30 irq_work_single+0xaf/0x160 run_irq_workd+0x91/0xc0 smpboot_thread_fn+0x24d/0x3b0 kthread+0x3bd/0x410 ret_from_fork+0x35/0x40 ret_from_fork_asm+0x1a/0x30 no locks held by irq_work/8/88. irq event stamp: 200272 hardirqs last enabled at (200272): [<ffffffffb0f56121>] finish_task_switch+0x131/0x320 hardirqs last disabled at (200271): [<ffffffffb25c7859>] __schedule+0x129/0xd70 softirqs last enabled at (0): [<ffffffffb0ee093f>] copy_process+0x4df/0x1cc0 softirqs last disabled at (0): [<0000000000000000>] 0x0 ------------------------------------------------------------------------ The problem is that irq-work handlers run with interrupts enabled, which means that rcu_preempt_deferred_qs_handler() could be interrupted, and that interrupt handler might contain an RCU read-side critical section, which might invoke rcu_read_unlock_special(). In the strict KCSAN mode of operation used by RCU, this constitutes a data race on the ->defer_qs_iw_pending field. This commit therefore disables interrupts across the portion of the rcu_preempt_deferred_qs_handler() that updates the ->defer_qs_iw_pending field. This suffices because this handler is not a fast path.

Gravité et risque d'exploitation

CVE-2025-39749 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.17 %, ce qui la place devant 6.5 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <90de9c94ea72327cfa9c2c9f6113c23a513af60b, <=6.1.*, <=6.12.*, <=6.16.*, 6.17, 0, <b55947b725f190396f475d5d0c59aa855a4d8895, <=6.15.*, 5.4.297, 6.6.103, <b5de8d80b5d049f051b95d9b1ee50ae4ab656124, <f937759c7432d6151b73e1393b6517661813d506, <=5.10.*, <=6.6.*, 5.15.190, 5.3, <=5.4.*, 6.12.43, <5.3, <0ad84d62217488e679ecc90e8628980dcc003de3, 6.1.149, 6.16.2, 5.10.241, <=*, <e35e711c78c8a4c43330c0dcb1c4d507a19c20f4, <=5.15.*, <55e11f6776798b27cf09a7aa0d718415d4fc9cf5, <90c09d57caeca94e6f3f87c49e96a91edd40cbfd, <74f58f382a7c8333f8d09701aefaa25913bdbe0e, 6.15.11, 0864f057b050bc6dd68106b3185e02db5140012d) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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