{"id":"CVE-2026-52947","summary":"net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove\n\nIn qrtr_port_remove(), the socket reference count is decremented via\n__sock_put() before the port is removed from the qrtr_ports XArray and\nbefore the RCU grace period elapses.\n\nThis breaks the fundamental RCU update paradigm. It exposes a race\nwindow where a concurrent RCU reader (such as qrtr_reset_ports() or\nqrtr_port_lookup()) can obtain a pointer to the socket from the XArray,\nand attempt to call sock_hold() on a socket whose reference count has\nalready dropped to zero.\n\nThis exact race condition was hit during syzkaller fuzzing, leading to\nthe following refcount saturation warning and a potential Use-After-Free:\n\n  refcount_t: saturated; leaking memory.\n  WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0\n  Modules linked in: qrtr(+) bochs drm_shmem_helper ...\n  Call Trace:\n   \u003cTASK\u003e\n   qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr]\n   __qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr]\n   qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr]\n   kernel_bind+0xe4/0x120 net/socket.c:3592\n   qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr]\n   qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr]\n   do_one_initcall+0xf5/0x5e0 init/main.c:1283\n   ...\n   \u003c/TASK\u003e\n\nFix this by deferring the reference count decrement until after the\nxa_erase() and the synchronize_rcu() complete.\n\n(Note: The v1 of this patch incorrectly replaced __sock_put() with\nsock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove()\nstill hold a reference to the socket, so freeing the socket memory here\nwould lead to a subsequent UAF in the caller. Thus, the __sock_put() is\nkept, but only repositioned to close the RCU race.)","modified":"2026-07-12T03:54:50.950990991Z","published":"2026-06-24T16:26:05.062Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52947.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/03bfa95e452e2b6ccd76a332060ae4feaf5ad84d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2047c2aa0963bb2872fd722300a15bcb441a4c00"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2aa4c12723fe432e623462a3be42a197a128722b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3b20ec8f31e8a6a6782243f473b0abd3463621df"},{"type":"WEB","url":"https://git.kernel.org/stable/c/474293d90880622fde9d2430fb0165767090f7b3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7de2d447072be3b1a76793f034432338fc9c494b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a2171131ecda1ed61a594a1eb715e75fdad0fef5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ab269990ed58143a92a263be1bee626d82ac03da"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52947.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52947"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"bdabad3e363d825ddf9679dd431cca0b2c30f881"},{"fixed":"2aa4c12723fe432e623462a3be42a197a128722b"},{"fixed":"03bfa95e452e2b6ccd76a332060ae4feaf5ad84d"},{"fixed":"474293d90880622fde9d2430fb0165767090f7b3"},{"fixed":"2047c2aa0963bb2872fd722300a15bcb441a4c00"},{"fixed":"7de2d447072be3b1a76793f034432338fc9c494b"},{"fixed":"ab269990ed58143a92a263be1bee626d82ac03da"},{"fixed":"3b20ec8f31e8a6a6782243f473b0abd3463621df"},{"fixed":"a2171131ecda1ed61a594a1eb715e75fdad0fef5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52947.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.7.0"},{"fixed":"5.10.259"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.210"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.176"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.143"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.94"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52947.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}