CVE-2026-89983

Summary

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

i2c: core: fix debugfs UAF on adapter removal

i2c_del_adapter() frees the adapter's debugfs directory before it unregisters the adapter device, but the new_device sysfs attribute stays writable until device_del(). A write racing with removal still reaches i2c_device_probe(), which passes the freed adap->debugfs to debugfs_create_dir() as the new client's parent:

BUG: KASAN: slab-use-after-free in lookup_noperm_common+0x407/0x430 Read of size 4 at addr ffff88803ef87810 by task syz.0.61/6090 lookup_noperm_common+0x407/0x430 simple_start_creating+0x9c/0x110 debugfs_start_creating+0xdb/0x1a0 debugfs_create_dir+0x24/0x350 i2c_device_probe+0x814/0xbf0

It's technically possible to create a client after i2c_deregister_clients has run. That client will never be unregistered and make wait_for_completion hang.

Close the window by removing the new_device attribute at the start of i2c_del_adapter(). device_remove_file() will drain any clients left.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/dc33a9762538b3250ed6b5644a4d44c748be33a6
• https://git.kernel.org/stable/c/1f1bcd4eca6caa3e4258d9a31925112539406eb6
• https://git.kernel.org/stable/c/f9094ace03e0a532cc6505d2e97b61ae738da4ed
• https://git.kernel.org/stable/c/643fb872aa04342d27dbef52b2b3cf3fe71b2c7b
• https://git.kernel.org/stable/c/112b3d48084c820bbccf41d9783fd122e3ac4cb0
• https://git.kernel.org/stable/c/552836be2d95c688eede6371f85532abe1a71232
• https://git.kernel.org/stable/c/b15b548d52b43ba8ac4652bc2c7244a8dd1e9622

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