Description (CNA)
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 (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before 2d5e320b7ab9b25229ac4331541964a58b5e1d29; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before 203a965bf2ab43130778d8214fb0c3c8c2d19cdf; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before 23da32e88627e63e0864f59f4c63a2dc0ab851a3; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before d663fbf28b2eebe665bb9cf828d7d528e5a8707e; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before e2e255d07723c330dded8e576ce28a8d23a692ce; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before c00164c9e7fa6145886ad666806cb5347895de5c; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before 1f4f02b336c3be125c8fcf87df73db2e0e028b8b; affected b84d435cc228e87951f3bbabf6cc4a5f25d5fb16 before b81dde13cc163450dcb402dcc915ef13ba241e01 |
| Linux / Linux | affected 3.3; unaffected 0 before 3.3; unaffected 5.10.261 through 5.10.*; unaffected 5.15.212 through 5.15.*; unaffected 6.1.178 through 6.1.*; unaffected 6.6.145 through 6.6.*; unaffected 6.12.96 through 6.12.*; unaffected 6.18.39 through 6.18.*; unaffected 7.1.4 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
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