CVE-2026-64251

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

pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next()

pwrseq_debugfs_seq_next() declares next with __free(put_device), which causes put_device() to be called on the returned pointer when the variable goes out of scope. This results in a use-after-free since the seq_file framework receives a pointer whose reference has already been dropped.

Simply removing __free(put_device) would fix the UAF but would leak the reference acquired by bus_find_next_device(), as stop() only calls up_read(&pwrseq_sem) and never releases the device reference.

Fix this by making the reference counting consistent across all seq_file callbacks, matching the standard pattern used by PCI and SCSI:

• start(): use get_device() so it returns a referenced pointer.
• next(): explicitly put_device(curr) to release the previous devices reference (no NULL check needed - the seq_file framework only calls next() while the previous return was non-NULL).
• stop(): put_device(data) to release the last iterated devices reference, with a NULL guard since stop() may be called with NULL when start() returned NULL or next() reached end-of-sequence.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/257595adf9dac15ae1edd9d07753fbc576a7583d
• https://git.kernel.org/stable/c/73569a44fca2992f0ca4a4c0104069741b9873a0
• https://git.kernel.org/stable/c/ba0b9f04c7a5f9887b8ce672eaf049502c0548ec
• https://git.kernel.org/stable/c/e91df6d273445c03f5aa302bfe147eda33d45794