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.
Metrics
Affected Vendors & Products
| Vendors | Products |
|---|---|
| Linux |
|
No data.
No data.
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| Vendors | Products |
|---|
References
History
Mon, 10 Aug 2026 20:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-469 |
Mon, 10 Aug 2026 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | debugobjects: Plug race against a concurrent OOM disable | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-10T11:51:45.149Z
Reserved: 2026-07-30T09:28:09.367Z
Link: CVE-2026-68090
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-08-10T20:00:03Z