Description
In the Linux kernel, the following vulnerability has been resolved: debugobjects: Plug race against a concurrent OOM disable syzbot reported a puzzling splat: WARNING: kernel/time/hrtimer.c:443 at stub_timer+0xa/0x20 stub_timer() is installed as timer callback function in hrtimer_fixup_assert_init(), which is invoked when debug_object_assert_init() can't find a shadow object. In that case debug objects emits a warning about it before invoking the fixup. Though the provided console log lacks this warning and instead has the following a few seconds before the splat: ODEBUG: Out of memory. ODEBUG disabled So the object was looked up in debug_object_assert_init() and the lookup failed due a concurrent out of memory situation which disabled debug objects and freed the shadow objects: debug_object_assert_init() if (!debug_objects_enabled) return; obj = alloc(); if (!obj) { // Out of memory debug_objects_enabled = false; free_objects(); obj = lookup_or_alloc(); // The lookup failed because the other side // removed the objects, so this returns // an error code as the object in question // is not statically initialized if (!IS_ERR_OR_NULL(obj)) return; if (!obj) { debug_oom(); return; } print(...) if (!debug_objects_enabled) return; fixup(...) The debug object splat is skipped because debug_objects_enabled is false, but the fixup callback is invoked unconditionally, which makes the timer disfunctional. This is only a problem in debug_object_assert_init() and debug_object_activate() as both have to handle statically initialized objects and therefore must handle the error pointer return case gracefully. All other places only handle the found/not found case and the NULL pointer return is a signal for OOM. Otherwise they get a valid shadow object. Plug the hole by checking whether debug objects are still enabled before invoking the print and fixup function in those two places.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < 2d5e320b7ab9b25229ac4331541964a58b5e1d29affectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < 203a965bf2ab43130778d8214fb0c3c8c2d19cdfaffectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < 23da32e88627e63e0864f59f4c63a2dc0ab851a3affectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < d663fbf28b2eebe665bb9cf828d7d528e5a8707eaffectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < e2e255d07723c330dded8e576ce28a8d23a692ceaffectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < c00164c9e7fa6145886ad666806cb5347895de5caffectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < 1f4f02b336c3be125c8fcf87df73db2e0e028b8baffectedb84d435cc228e87951f3bbabf6cc4a5f25d5fb16 to < b81dde13cc163450dcb402dcc915ef13ba241e01affected
Linux Linux
Default version status: affected
3.3affected0 to < 3.3unaffected5.10.261 to ≤ 5.10.*unaffected5.15.212 to ≤ 5.15.*unaffected6.1.178 to ≤ 6.1.*unaffected6.6.145 to ≤ 6.6.*unaffected6.12.96 to ≤ 6.12.*unaffected6.18.39 to ≤ 6.18.*unaffected7.1.4 to ≤ 7.1.*unaffected7.2 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/2d5e320b7ab9b25229ac4331541964a58b5e1d29 ↗
- https://git.kernel.org/stable/c/203a965bf2ab43130778d8214fb0c3c8c2d19cdf ↗
- https://git.kernel.org/stable/c/23da32e88627e63e0864f59f4c63a2dc0ab851a3 ↗
- https://git.kernel.org/stable/c/d663fbf28b2eebe665bb9cf828d7d528e5a8707e ↗
- https://git.kernel.org/stable/c/e2e255d07723c330dded8e576ce28a8d23a692ce ↗
- https://git.kernel.org/stable/c/c00164c9e7fa6145886ad666806cb5347895de5c ↗
- https://git.kernel.org/stable/c/1f4f02b336c3be125c8fcf87df73db2e0e028b8b ↗
- https://git.kernel.org/stable/c/b81dde13cc163450dcb402dcc915ef13ba241e01 ↗