net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove

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Summary

CVECVE-2026-52947
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-24 17:17:04 UTC
Updated2026-06-24 17:17:04 UTC
DescriptionIn 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.)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 2aa4c12723fe432e623462a3be42a197a128722b git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 03bfa95e452e2b6ccd76a332060ae4feaf5ad84d git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 474293d90880622fde9d2430fb0165767090f7b3 git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 2047c2aa0963bb2872fd722300a15bcb441a4c00 git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 7de2d447072be3b1a76793f034432338fc9c494b git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 ab269990ed58143a92a263be1bee626d82ac03da git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 3b20ec8f31e8a6a6782243f473b0abd3463621df git Not specified
CNA Linux Linux affected bdabad3e363d825ddf9679dd431cca0b2c30f881 a2171131ecda1ed61a594a1eb715e75fdad0fef5 git Not specified
CNA Linux Linux affected 4.7 Not specified
CNA Linux Linux unaffected 4.7 semver Not specified
CNA Linux Linux unaffected 5.10.259 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.210 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.176 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.143 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.94 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.36 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.13 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/3b20ec8f31e8a6a6782243f473b0abd3463621df 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a2171131ecda1ed61a594a1eb715e75fdad0fef5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/03bfa95e452e2b6ccd76a332060ae4feaf5ad84d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2aa4c12723fe432e623462a3be42a197a128722b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/474293d90880622fde9d2430fb0165767090f7b3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ab269990ed58143a92a263be1bee626d82ac03da 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7de2d447072be3b1a76793f034432338fc9c494b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2047c2aa0963bb2872fd722300a15bcb441a4c00 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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