Improper Update of Reference Count Affecting rv package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.18% (9th percentile)

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  • Snyk IDSNYK-CENTOS10-RV-17516164
  • published26 Jun 2026
  • disclosed24 Jun 2026

Introduced: 24 Jun 2026

NewCVE-2026-52947  (opens in a new tab)
CWE-911  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 rv.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rv package and not the rv package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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.)

CVSS Base Scores

version 3.1