In the Linux kernel, the following vulnerability has been resolved:
net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove
In qrtr_port_remove(), the socket reference count is decremented via
__sock_put() before the port is removed from the qrtr_ports XArray and
before the RCU grace period elapses.
This breaks the fundamental RCU update paradigm. It exposes a race
window where a concurrent RCU reader (such as qrtr_reset_ports() or
qrtr_port_lookup()) can obtain a pointer to the socket from the XArray,
and attempt to call sock_hold() on a socket whose reference count has
already dropped to zero.
This exact race condition was hit during syzkaller fuzzing, leading to
the following refcount saturation warning and a potential Use-After-Free:
refcount_t: saturated; leaking memory.
WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0
Modules linked in: qrtr(+) bochs drm_shmem_helper ...
Call Trace:
<TASK>
qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr]
__qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr]
qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr]
kernel_bind+0xe4/0x120 net/socket.c:3592
qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr]
qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr]
do_one_initcall+0xf5/0x5e0 init/main.c:1283
...
</TASK>
Fix this by deferring the reference count decrement until after the
xa_erase() and the synchronize_rcu() complete.
(Note: The v1 of this patch incorrectly replaced __sock_put() with
sock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove()
still hold a reference to the socket, so freeing the socket memory here
would lead to a subsequent UAF in the caller. Thus, the __sock_put() is
kept, but only repositioned to close the RCU race.)
References
Configurations
Configuration 1 (hide)
|
History
14 Jul 2026, 16:58
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/03bfa95e452e2b6ccd76a332060ae4feaf5ad84d - Patch | |
| References | () https://git.kernel.org/stable/c/2047c2aa0963bb2872fd722300a15bcb441a4c00 - Patch | |
| References | () https://git.kernel.org/stable/c/2aa4c12723fe432e623462a3be42a197a128722b - Patch | |
| References | () https://git.kernel.org/stable/c/3b20ec8f31e8a6a6782243f473b0abd3463621df - Patch | |
| References | () https://git.kernel.org/stable/c/474293d90880622fde9d2430fb0165767090f7b3 - Patch | |
| References | () https://git.kernel.org/stable/c/7de2d447072be3b1a76793f034432338fc9c494b - Patch | |
| References | () https://git.kernel.org/stable/c/a2171131ecda1ed61a594a1eb715e75fdad0fef5 - Patch | |
| References | () https://git.kernel.org/stable/c/ab269990ed58143a92a263be1bee626d82ac03da - Patch | |
| CWE | CWE-416 | |
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc7:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:* |
|
| First Time |
Linux linux Kernel
Linux |
28 Jun 2026, 08:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
24 Jun 2026, 17:17
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-06-24 17:17
Updated : 2026-07-14 16:58
NVD link : CVE-2026-52947
Mitre link : CVE-2026-52947
CVE.ORG link : CVE-2026-52947
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free