In the Linux kernel, the following vulnerability has been resolved:
gpib: fix use-after-free in IO ioctl handlers
The IBRD, IBWRT, IBCMD, and IBWAIT ioctl handlers use a gpib_descriptor
pointer after board->big_gpib_mutex has been released. A concurrent
IBCLOSEDEV ioctl can free the descriptor via close_dev_ioctl() during
this window, causing a use-after-free.
The IO handlers (read_ioctl, write_ioctl, command_ioctl) explicitly
release big_gpib_mutex before calling their handler. wait_ioctl() is
called with big_gpib_mutex held, but ibwait() releases it internally
when wait_mask is non-zero. In all four cases, the descriptor pointer
obtained from handle_to_descriptor() becomes unprotected.
Fix this by introducing a kernel-only descriptor_busy reference count
in struct gpib_descriptor. Each handler atomically increments
descriptor_busy under file_priv->descriptors_mutex before releasing the
lock, and decrements it when done. close_dev_ioctl() checks
descriptor_busy under the same lock and rejects the close with -EBUSY
if the count is non-zero.
A reference count rather than a simple flag is necessary because
multiple handlers can operate on the same descriptor concurrently
(e.g. IBRD and IBWAIT on the same handle from different threads).
A separate counter is needed because io_in_progress can be cleared from
unprivileged userspace via the IBWAIT ioctl (through general_ibstatus()
with set_mask containing CMPL), which would allow an attacker to bypass
a check based solely on io_in_progress. The new descriptor_busy
counter is only modified by the kernel IO paths.
The lock ordering is consistent (big_gpib_mutex -> descriptors_mutex)
and the handlers only hold descriptors_mutex briefly during the lookup,
so there is no deadlock risk and no impact on IO throughput.
References
Configurations
Configuration 1 (hide)
|
History
11 May 2026, 17:56
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/28c75dd143ead62e0dfac564c79d251e21d5d74b - Patch | |
| References | () https://git.kernel.org/stable/c/cae26eff1b56d78bed7873cf3e60a2b1bdd4da6c - Patch | |
| References | () https://git.kernel.org/stable/c/d1857f8296dceb75d00ab857fc3c61bc00c7f5c6 - Patch | |
| CWE | CWE-416 | |
| First Time |
Linux linux Kernel
Linux |
|
| CPE | cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
03 May 2026, 07:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
01 May 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-01 15:16
Updated : 2026-05-11 17:56
NVD link : CVE-2026-31769
Mitre link : CVE-2026-31769
CVE.ORG link : CVE-2026-31769
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free