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| author | Adam Crosser <adam.crosser@praetorian.com> | 2026-04-24 15:37:47 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-05-23 14:47:34 +0300 |
| commit | c4faab452b3c1ada003d49c477609dd80523b9bf (patch) | |
| tree | 831181e62f8d04fc240e0f50e85fe1203b096266 | |
| parent | 6be50f680a3b2e3c87ac5faf5eddf44bb3ad6558 (diff) | |
| download | linux-c4faab452b3c1ada003d49c477609dd80523b9bf.tar.xz | |
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().
Fixes: d1857f8296dc ("gpib: fix use-after-free in IO ioctl handlers")
Reported-by: Ruikai Peng <ruikai@pwno.io>
Signed-off-by: Adam Crosser <adam.crosser@praetorian.com>
Link: https://patch.msgid.link/20260424123750.855863-1-adam.r.crosser@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/gpib/common/gpib_os.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/gpib/common/gpib_os.c b/drivers/gpib/common/gpib_os.c index 4c6c43f012c8..69f6aa73ab9a 100644 --- a/drivers/gpib/common/gpib_os.c +++ b/drivers/gpib/common/gpib_os.c @@ -1010,7 +1010,6 @@ static int command_ioctl(struct gpib_file_private *file_priv, userbuf += bytes_written; if (retval < 0) { atomic_set(&desc->io_in_progress, 0); - atomic_dec(&desc->descriptor_busy); wake_up_interruptible(&board->wait); break; |