| From bippy-7c5fe7eed585 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-21983: mm/slab/kvfree_rcu: Switch to WQ_MEM_RECLAIM wq |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm/slab/kvfree_rcu: Switch to WQ_MEM_RECLAIM wq |
| |
| Currently kvfree_rcu() APIs use a system workqueue which is |
| "system_unbound_wq" to driver RCU machinery to reclaim a memory. |
| |
| Recently, it has been noted that the following kernel warning can |
| be observed: |
| |
| <snip> |
| workqueue: WQ_MEM_RECLAIM nvme-wq:nvme_scan_work is flushing !WQ_MEM_RECLAIM events_unbound:kfree_rcu_work |
| WARNING: CPU: 21 PID: 330 at kernel/workqueue.c:3719 check_flush_dependency+0x112/0x120 |
| Modules linked in: intel_uncore_frequency(E) intel_uncore_frequency_common(E) skx_edac(E) ... |
| CPU: 21 UID: 0 PID: 330 Comm: kworker/u144:6 Tainted: G E 6.13.2-0_g925d379822da #1 |
| Hardware name: Wiwynn Twin Lakes MP/Twin Lakes Passive MP, BIOS YMM20 02/01/2023 |
| Workqueue: nvme-wq nvme_scan_work |
| RIP: 0010:check_flush_dependency+0x112/0x120 |
| Code: 05 9a 40 14 02 01 48 81 c6 c0 00 00 00 48 8b 50 18 48 81 c7 c0 00 00 00 48 89 f9 48 ... |
| RSP: 0018:ffffc90000df7bd8 EFLAGS: 00010082 |
| RAX: 000000000000006a RBX: ffffffff81622390 RCX: 0000000000000027 |
| RDX: 00000000fffeffff RSI: 000000000057ffa8 RDI: ffff88907f960c88 |
| RBP: 0000000000000000 R08: ffffffff83068e50 R09: 000000000002fffd |
| R10: 0000000000000004 R11: 0000000000000000 R12: ffff8881001a4400 |
| R13: 0000000000000000 R14: ffff88907f420fb8 R15: 0000000000000000 |
| FS: 0000000000000000(0000) GS:ffff88907f940000(0000) knlGS:0000000000000000 |
| CR2: 00007f60c3001000 CR3: 000000107d010005 CR4: 00000000007726f0 |
| PKRU: 55555554 |
| Call Trace: |
| <TASK> |
| ? __warn+0xa4/0x140 |
| ? check_flush_dependency+0x112/0x120 |
| ? report_bug+0xe1/0x140 |
| ? check_flush_dependency+0x112/0x120 |
| ? handle_bug+0x5e/0x90 |
| ? exc_invalid_op+0x16/0x40 |
| ? asm_exc_invalid_op+0x16/0x20 |
| ? timer_recalc_next_expiry+0x190/0x190 |
| ? check_flush_dependency+0x112/0x120 |
| ? check_flush_dependency+0x112/0x120 |
| __flush_work.llvm.1643880146586177030+0x174/0x2c0 |
| flush_rcu_work+0x28/0x30 |
| kvfree_rcu_barrier+0x12f/0x160 |
| kmem_cache_destroy+0x18/0x120 |
| bioset_exit+0x10c/0x150 |
| disk_release.llvm.6740012984264378178+0x61/0xd0 |
| device_release+0x4f/0x90 |
| kobject_put+0x95/0x180 |
| nvme_put_ns+0x23/0xc0 |
| nvme_remove_invalid_namespaces+0xb3/0xd0 |
| nvme_scan_work+0x342/0x490 |
| process_scheduled_works+0x1a2/0x370 |
| worker_thread+0x2ff/0x390 |
| ? pwq_release_workfn+0x1e0/0x1e0 |
| kthread+0xb1/0xe0 |
| ? __kthread_parkme+0x70/0x70 |
| ret_from_fork+0x30/0x40 |
| ? __kthread_parkme+0x70/0x70 |
| ret_from_fork_asm+0x11/0x20 |
| </TASK> |
| ---[ end trace 0000000000000000 ]--- |
| <snip> |
| |
| To address this switch to use of independent WQ_MEM_RECLAIM |
| workqueue, so the rules are not violated from workqueue framework |
| point of view. |
| |
| Apart of that, since kvfree_rcu() does reclaim memory it is worth |
| to go with WQ_MEM_RECLAIM type of wq because it is designed for |
| this purpose. |
| |
| The Linux kernel CVE team has assigned CVE-2025-21983 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.12 with commit 6c6c47b063b593785202be158e61fe5c827d6677 and fixed in 6.12.20 with commit a74979dce9e9c61f6d797c3761020252c4d8dc63 |
| Issue introduced in 6.12 with commit 6c6c47b063b593785202be158e61fe5c827d6677 and fixed in 6.13.8 with commit 656e35bf66a11e1adde44c4c12050086dc39f241 |
| Issue introduced in 6.12 with commit 6c6c47b063b593785202be158e61fe5c827d6677 and fixed in 6.14 with commit dfd3df31c9db752234d7d2e09bef2aeabb643ce4 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-21983 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| mm/slab_common.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/a74979dce9e9c61f6d797c3761020252c4d8dc63 |
| https://git.kernel.org/stable/c/656e35bf66a11e1adde44c4c12050086dc39f241 |
| https://git.kernel.org/stable/c/dfd3df31c9db752234d7d2e09bef2aeabb643ce4 |
