CVE-2024-50140: sched/core: Disable page allocation in task_tick_mm_cid()
First published: Thu Nov 07 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: sched/core: Disable page allocation in task_tick_mm_cid() With KASAN and PREEMPT_RT enabled, calling task_work_add() in task_tick_mm_cid() may cause the following splat. [ 63.696416] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 [ 63.696416] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 610, name: modprobe [ 63.696416] preempt_count: 10001, expected: 0 [ 63.696416] RCU nest depth: 1, expected: 1 This problem is caused by the following call trace. sched_tick() [ acquire rq->__lock ] -> task_tick_mm_cid() -> task_work_add() -> __kasan_record_aux_stack() -> kasan_save_stack() -> stack_depot_save_flags() -> alloc_pages_mpol_noprof() -> __alloc_pages_noprof() -> get_page_from_freelist() -> rmqueue() -> rmqueue_pcplist() -> __rmqueue_pcplist() -> rmqueue_bulk() -> rt_spin_lock() The rq lock is a raw_spinlock_t. We can't sleep while holding it. IOW, we can't call alloc_pages() in stack_depot_save_flags(). The task_tick_mm_cid() function with its task_work_add() call was introduced by commit 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid") in v6.4 kernel. Fortunately, there is a kasan_record_aux_stack_noalloc() variant that calls stack_depot_save_flags() while not allowing it to allocate new pages. To allow task_tick_mm_cid() to use task_work without page allocation, a new TWAF_NO_ALLOC flag is added to enable calling kasan_record_aux_stack_noalloc() instead of kasan_record_aux_stack() if set. The task_tick_mm_cid() function is modified to add this new flag. The possible downside is the missing stack trace in a KASAN report due to new page allocation required when task_work_add_noallloc() is called which should be rare.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | >=6.4<6.6.59 | |
| Linux Kernel | >=6.7<6.11.6 | |
| Linux Kernel | =6.12-rc1 | |
| Linux Kernel | =6.12-rc2 | |
| Linux Kernel | =6.12-rc3 |
Never miss a vulnerability like this again
Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.
Reference Links
Frequently Asked Questions
What is the severity of CVE-2024-50140?
CVE-2024-50140 is considered a moderate severity vulnerability affecting the Linux kernel.
How do I fix CVE-2024-50140?
To mitigate CVE-2024-50140, update to a patched version of the Linux kernel, such as 5.10.223-1, 6.1.123-1, or later.
Which versions of the Linux kernel are affected by CVE-2024-50140?
CVE-2024-50140 affects Linux kernel versions from 6.4 to 6.6.59, and specific release candidates 6.12-rc1, 6.12-rc2, and 6.12-rc3.
What triggers the vulnerability in CVE-2024-50140?
CVE-2024-50140 is triggered by calling task_work_add() within task_tick_mm_cid() when KASAN and PREEMPT_RT are enabled.
Is CVE-2024-50140 related to memory allocation issues?
Yes, CVE-2024-50140 involves an issue with page allocation that can lead to kernel errors under certain conditions.
- agent/title
- agent/references
- agent/description
- agent/type
- agent/first-publish-date
- agent/author
- agent/event
- agent/severity
- agent/remedy
- agent/softwarecombine
- collector/mitre-cve
- source/MITRE
- agent/last-modified-date
- agent/source
- agent/tags
- collector/nvd-api
- source/NVD
- agent/software-canonical-lookup
- agent/software-canonical-lookup-request
- vendor/linux
- canonical/linux kernel
- version/linux kernel/6.4
- version/linux kernel/6.7
- version/linux kernel/6.12-rc1
- version/linux kernel/6.12-rc2
- version/linux kernel/6.12-rc3