{"id":"AZL-53537","summary":"CVE-2024-50140 affecting package kernel for versions less than 6.6.64.2-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/core: Disable page allocation in task_tick_mm_cid()\n\nWith KASAN and PREEMPT_RT enabled, calling task_work_add() in\ntask_tick_mm_cid() may cause the following splat.\n\n[   63.696416] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48\n[   63.696416] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 610, name: modprobe\n[   63.696416] preempt_count: 10001, expected: 0\n[   63.696416] RCU nest depth: 1, expected: 1\n\nThis problem is caused by the following call trace.\n\n  sched_tick() [ acquire rq-\u003e__lock ]\n   -\u003e task_tick_mm_cid()\n    -\u003e task_work_add()\n     -\u003e __kasan_record_aux_stack()\n      -\u003e kasan_save_stack()\n       -\u003e stack_depot_save_flags()\n        -\u003e alloc_pages_mpol_noprof()\n         -\u003e __alloc_pages_noprof()\n\t  -\u003e get_page_from_freelist()\n\t   -\u003e rmqueue()\n\t    -\u003e rmqueue_pcplist()\n\t     -\u003e __rmqueue_pcplist()\n\t      -\u003e rmqueue_bulk()\n\t       -\u003e rt_spin_lock()\n\nThe rq lock is a raw_spinlock_t. We can't sleep while holding\nit. IOW, we can't call alloc_pages() in stack_depot_save_flags().\n\nThe task_tick_mm_cid() function with its task_work_add() call was\nintroduced by commit 223baf9d17f2 (\"sched: Fix performance regression\nintroduced by mm_cid\") in v6.4 kernel.\n\nFortunately, there is a kasan_record_aux_stack_noalloc() variant that\ncalls stack_depot_save_flags() while not allowing it to allocate\nnew pages.  To allow task_tick_mm_cid() to use task_work without\npage allocation, a new TWAF_NO_ALLOC flag is added to enable calling\nkasan_record_aux_stack_noalloc() instead of kasan_record_aux_stack()\nif set. The task_tick_mm_cid() function is modified to add this new flag.\n\nThe possible downside is the missing stack trace in a KASAN report due\nto new page allocation required when task_work_add_noallloc() is called\nwhich should be rare.","modified":"2026-04-21T04:35:17.059587Z","published":"2024-11-07T10:15:05Z","upstream":["CVE-2024-50140"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-50140"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.64.2-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-53537.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}