CVE-2026-72482

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

gpib: fix double decrement of descriptor_busy in command_ioctl()

commit d1857f8296dc ("gpib: fix use-after-free in IO ioctl handlers")

introduced a descriptor_busy reference counter to pin struct

gpib_descriptor across IO ioctl operations. In command_ioctl(), the

error path inside the loop decrements descriptor_busy and breaks, but

execution then falls through to the unconditional decrement after the

loop, underflowing the counter to -1.

This re-enables the use-after-free that the original fix was meant to

prevent: a concurrent close_dev_ioctl() sees descriptor_busy == 0 on

an actively-used descriptor and frees it.

Remove the early decrement from the error path. The post-loop

decrement already handles all exit paths, matching the correct pattern

used in read_ioctl() and write_ioctl().