CVE-2026-97604

fbdev: vfb: defer cleanup until the last reference

State: Published
Severity: Not scored
Published: Sep 25, 2026
Updated: Oct 19, 2026
Reserved: Sep 24, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

fbdev: vfb: defer cleanup until the last reference

FBIOGETCMAP takes a shallow snapshot of info->cmap and performs the usercopy after dropping info->lock. vfb_remove() frees the colormap immediately after unregistering the framebuffer, even when an open file still holds a reference to fb_info. A concurrent driver unbind can therefore free the colormap while the ioctl copies it to userspace.

KASAN reports:

BUG: KASAN: slab-use-after-free in _copy_to_user Read of size 512 by task poc/125

_copy_to_user (./include/linux/instrumented.h:129 ./include/linux/uaccess.h:201 lib/usercopy.c:24) fb_cmap_to_user (./include/linux/uaccess.h:230 drivers/video/fbdev/core/fbcmap.c:211) do_fb_ioctl (drivers/video/fbdev/core/fb_chrdev.c:114)

Allocated by task 1: fb_alloc_cmap_gfp (./include/linux/slab.h:973 ./include/linux/slab.h:1290 drivers/video/fbdev/core/fbcmap.c:108) vfb_probe (drivers/video/fbdev/vfb.c:459)

Freed by task 124: fb_dealloc_cmap (drivers/video/fbdev/core/fbcmap.c:151) vfb_remove (drivers/video/fbdev/vfb.c:489)

unregister_framebuffer() drops the registration reference, and fbdev calls fb_destroy after the last put_fb_info(). Move the registered framebuffer's cleanup into an fb_destroy callback so its colormap and screen buffer stay alive until all file references have been released.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before bf49eac7ed11aabd0b9b790c062742a8e4be97c6Affected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 040ce3950f64a11e9ee5646c8aaa91fd2e29e245Affected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before ab664e279eb2a68e55895dd115a9488807280f07Affected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before de5a0eda59fe4b3eacd1a67c992e54766bb6683fAffected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 86356f13598f59f5acb1754895747dcdaf65a254Affected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 5ff1effb047e465cde193d7df95988aa1520035eAffected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 3c91e51a53cf805e551e5dc8149cd0539a6dbb9dAffected 5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before a0a34a40ed299c9c7cff6af163a5b883ee9d6d73Affected
LinuxLinux	2.6.30Affected before 2.6.30Not affected 5.10.271 through 5.10.Not affected 5.15.222 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.111 through 6.12.Not affected 6.18.53 through 6.18.Not affected 7.2.7 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before bf49eac7ed11aabd0b9b790c062742a8e4be97c6Affected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 040ce3950f64a11e9ee5646c8aaa91fd2e29e245Affected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before ab664e279eb2a68e55895dd115a9488807280f07Affected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before de5a0eda59fe4b3eacd1a67c992e54766bb6683fAffected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 86356f13598f59f5acb1754895747dcdaf65a254Affected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 5ff1effb047e465cde193d7df95988aa1520035eAffected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before 3c91e51a53cf805e551e5dc8149cd0539a6dbb9dAffected
5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a to before a0a34a40ed299c9c7cff6af163a5b883ee9d6d73Affected

LinuxLinux

2.6.30Affected
before 2.6.30Not affected
5.10.271 through 5.10.*Not affected
5.15.222 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.111 through 6.12.*Not affected
6.18.53 through 6.18.*Not affected
7.2.7 through 7.2.*Not affected
7.3 and laterNot affected

References

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