CVE-2026-43327

Description

In the Linux kernel, the following vulnerability has been resolved: USB: dummy-hcd: Fix locking/synchronization error Syzbot testing was able to provoke an addressing exception and crash in the usb_gadget_udc_reset() routine in drivers/usb/gadgets/udc/core.c, resulting from the fact that the routine was called with a second ("driver") argument of NULL. The bad caller was set_link_state() in dummy_hcd.c, and the problem arose because of a race between a USB reset and driver unbind. These sorts of races were not supposed to be possible; commit 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"), along with a few followup commits, was written specifically to prevent them. As it turns out, there are (at least) two errors remaining in the code. Another patch will address the second error; this one is concerned with the first. The error responsible for the syzbot crash occurred because the stop_activity() routine will sometimes drop and then re-acquire the dum->lock spinlock. A call to stop_activity() occurs in set_link_state() when handling an emulated USB reset, after the test of dum->ints_enabled and before the increment of dum->callback_usage. This allowed another thread (doing a driver unbind) to sneak in and grab the spinlock, and then clear dum->ints_enabled and dum->driver. Normally this other thread would have to wait for dum->callback_usage to go down to 0 before it would clear dum->driver, but in this case it didn't have to wait since dum->callback_usage had not yet been incremented. The fix is to increment dum->callback_usage _before_ calling stop_activity() instead of after. Then the thread doing the unbind will not clear dum->driver until after the call to usb_gadget_udc_reset() safely returns and dum->callback_usage has been decremented again.

Gravité et risque d'exploitation

CVE-2026-43327 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 0.13 %, ce qui la place devant 2.0 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions 4.1.46, <=6.1.*, <218886b2ef2dea7627d3700ab0abaf4bf9d1161f, <4.2, <=6.12.*, a867d5b932ac4911d3f8a1e63505061b0c81f889, 7dbd8f4cabd96db5a50513de9d83a8105a5ffc81, 4.4.92, 0, 6.6.134, 7.0, <805b1833d6ed6da5086e610578a28e71bb54fbbb, <4.10, <616a63ff495df12863692ab3f9f7b84e3fa7a66d, 8590bc1da625dd4a589eac0fc3aa3cf4f400424d, <3.3, <cc97fb5969177cccce2e23b31298df220fc7570d, e39b17143a5b5aac81f066d455e5d3a9877eb3ae, <6350c7dd33ab481ef41c931a238361490c32d15c, <=5.10.*, <=6.6.*, <=6.19.*, <69ab97a693251d6a6093e630060a3c744fd58524, 4.9.55, <4.5, 4.13.6, 5.15.203, <=6.18.*, <efbd9441f1e769a7aae1813d497cec09cbdff031, 6.12.81, <791966f85b439b261bf19865cf1c07c065ffb4b4, <=*, e84b4a008365b7edbd842a063ae28d040a98db25, <4.14, 5.10.253, <=5.15.*, 7b416b9dac6ede26d4ca0c1a88b448b543623ff3, 3.16.52, <3.17, 6.1.168, 4f8ae1fcb0dfbb72a7678f81bf01fb7fc85c6715, 3.2.97, 6.18.22, 6.19.12, 4.14) 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

• https://git.kernel.org/stable/c/6350c7dd33ab481ef41c931a238361490c32d15c
• https://git.kernel.org/stable/c/cc97fb5969177cccce2e23b31298df220fc7570d
• https://git.kernel.org/stable/c/218886b2ef2dea7627d3700ab0abaf4bf9d1161f
• https://git.kernel.org/stable/c/791966f85b439b261bf19865cf1c07c065ffb4b4
• https://git.kernel.org/stable/c/805b1833d6ed6da5086e610578a28e71bb54fbbb
• https://git.kernel.org/stable/c/efbd9441f1e769a7aae1813d497cec09cbdff031
• https://git.kernel.org/stable/c/69ab97a693251d6a6093e630060a3c744fd58524
• https://git.kernel.org/stable/c/616a63ff495df12863692ab3f9f7b84e3fa7a66d