GHSA-QRRW-365J-CFXH
Vulnerability from github – Published: 2026-08-10 12:31 – Updated: 2026-08-10 12:31In 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": [],
"aliases": [
"CVE-2026-68090"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-10T12:17:21Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndebugobjects: Plug race against a concurrent OOM disable\n\nsyzbot reported a puzzling splat:\n\n WARNING: kernel/time/hrtimer.c:443 at stub_timer+0xa/0x20\n\nstub_timer() is installed as timer callback function in\nhrtimer_fixup_assert_init(), which is invoked when\ndebug_object_assert_init() can\u0027t find a shadow object. In that case debug\nobjects emits a warning about it before invoking the fixup.\n\nThough the provided console log lacks this warning and instead has the\nfollowing a few seconds before the splat:\n\n ODEBUG: Out of memory. ODEBUG disabled\n\nSo the object was looked up in debug_object_assert_init() and the lookup\nfailed due a concurrent out of memory situation which disabled debug\nobjects and freed the shadow objects:\n\ndebug_object_assert_init()\n if (!debug_objects_enabled)\n \treturn; obj = alloc();\n \t\t\t\tif (!obj) {\n\t\t\t\t\t\t\t// Out of memory\n \tdebug_objects_enabled = false;\n free_objects();\n obj = lookup_or_alloc();\n\n // The lookup failed because the other side\n // removed the objects, so this returns\n // an error code as the object in question\n // is not statically initialized\n\n\tif (!IS_ERR_OR_NULL(obj))\n \treturn;\n if (!obj) {\n \tdebug_oom();\n return;\n }\n\n print(...)\n if (!debug_objects_enabled)\n return;\n\n fixup(...)\n\nThe debug object splat is skipped because debug_objects_enabled is false,\nbut the fixup callback is invoked unconditionally, which makes the timer\ndisfunctional.\n\nThis is only a problem in debug_object_assert_init() and\ndebug_object_activate() as both have to handle statically initialized\nobjects and therefore must handle the error pointer return case\ngracefully. All other places only handle the found/not found case and the\nNULL pointer return is a signal for OOM. Otherwise they get a valid shadow\nobject.\n\nPlug the hole by checking whether debug objects are still enabled before\ninvoking the print and fixup function in those two places.",
"id": "GHSA-qrrw-365j-cfxh",
"modified": "2026-08-10T12:31:55Z",
"published": "2026-08-10T12:31:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68090"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1f4f02b336c3be125c8fcf87df73db2e0e028b8b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/203a965bf2ab43130778d8214fb0c3c8c2d19cdf"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/23da32e88627e63e0864f59f4c63a2dc0ab851a3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2d5e320b7ab9b25229ac4331541964a58b5e1d29"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b81dde13cc163450dcb402dcc915ef13ba241e01"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c00164c9e7fa6145886ad666806cb5347895de5c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d663fbf28b2eebe665bb9cf828d7d528e5a8707e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e2e255d07723c330dded8e576ce28a8d23a692ce"
}
],
"schema_version": "1.4.0",
"severity": []
}
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