CVE-2026-31578
In the Linux kernel, the following vulnerability has been resolved: media: as102: fix to not free memory after the device is registered in as102_usb_probe() In as102_usb driver, the following race condition occurs: ``` CPU0 CPU1 as102_usb_probe()…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.13%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: media: as102: fix to not free memory after the device is registered in as102_usb_probe() In as102_usb driver, the following race condition occurs: ``` CPU0 CPU1 as102_usb_probe() kzalloc(); // alloc as102_dev_t .... usb_register_dev(); fd = sys_open("/path/to/dev"); // open as102 fd .... usb_deregister_dev(); .... kfree(); // free as102_dev_t .... sys_close(fd); as102_release() // UAF!! as102_usb_release() kfree(); // DFB!! ``` When a USB character device registered with usb_register_dev() is later unregistered (via usb_deregister_dev() or disconnect), the device node is removed so new open() calls fail. However, file descriptors that are already open do not go away immediately: they remain valid until the last reference is dropped and the driver's .release() is invoked. In as102, as102_usb_probe() calls usb_register_dev() and then, on an error path, does usb_deregister_dev() and frees as102_dev_t right away. If userspace raced a successful open() before the deregistration, that open FD will later hit as102_release() --> as102_usb_release() and access or free as102_dev_t again, occur a race to use-after-free and double-free vuln. The fix is to never kfree(as102_dev_t) directly once usb_register_dev() has succeeded. After deregistration, defer freeing memory to .release(). In other words, let release() perform the last kfree when the final open FD is closed.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.13% probability · 3th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/07ceb444c8f627cf863864d4274b5a77769725ed
- https://git.kernel.org/stable/c/09e9206008b887aa553733bd915d73131071a086Patch
- https://git.kernel.org/stable/c/0d36653a3a821e5a974798adb347b3ea09332914
- https://git.kernel.org/stable/c/25d500cf391e384356a612b85cf60b353ad3cd0c
- https://git.kernel.org/stable/c/2eeae47a438694408189138048a786be99954032Patch
- https://git.kernel.org/stable/c/582fbecb3756330006fe1950762412a68c2cacd2Patch
- https://git.kernel.org/stable/c/7e5aedf6059cba2a669d86caeaf5a51f33ec85a1Patch
- https://git.kernel.org/stable/c/8bd29dbe03fc5b0f039ab2395ff37b64236d2f0cPatch
- https://git.kernel.org/stable/c/cb8092038e95dc1113a68e63762de40fff61ba71Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.