CVE-2025-37960

Published May 20, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: memblock: Accept allocated memory before use in memblock_double_array() When increasing the array size in memblock_double_array() and the slab is not yet available, a call to memblock_find_in_range() is used to reserve/allocate memory. However, the range returned may not have been accepted, which can result in a crash when booting an SNP guest: RIP: 0010:memcpy_orig+0x68/0x130 Code: ... RSP: 0000:ffffffff9cc03ce8 EFLAGS: 00010006 RAX: ff11001ff83e5000 RBX: 0000000000000000 RCX: fffffffffffff000 RDX: 0000000000000bc0 RSI: ffffffff9dba8860 RDI: ff11001ff83e5c00 RBP: 0000000000002000 R08: 0000000000000000 R09: 0000000000002000 R10: 000000207fffe000 R11: 0000040000000000 R12: ffffffff9d06ef78 R13: ff11001ff83e5000 R14: ffffffff9dba7c60 R15: 0000000000000c00 memblock_double_array+0xff/0x310 memblock_add_range+0x1fb/0x2f0 memblock_reserve+0x4f/0xa0 memblock_alloc_range_nid+0xac/0x130 memblock_alloc_internal+0x53/0xc0 memblock_alloc_try_nid+0x3d/0xa0 swiotlb_init_remap+0x149/0x2f0 mem_init+0xb/0xb0 mm_core_init+0x8f/0x350 start_kernel+0x17e/0x5d0 x86_64_start_reservations+0x14/0x30 x86_64_start_kernel+0x92/0xa0 secondary_startup_64_no_verify+0x194/0x19b Mitigate this by calling accept_memory() on the memory range returned before the slab is available. Prior to v6.12, the accept_memory() interface used a 'start' and 'end' parameter instead of 'start' and 'size', therefore the accept_memory() call must be adjusted to specify 'start + size' for 'end' when applying to kernels prior to v6.12.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: cgroup: Avoid iteration of dying tasks with zero refcount The commit 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()") extended the lifetime of tasks on the dying_tasks list. The iterators have provision to go through dying_tasks because of dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however, it was expected that such tasks can obtain a new reference (that is possible before cgroup_task_release()/put_task_struct_rcu_user()). The tasks after cgroup_task_release() and before cgroup_task_free() are subject to race when they may or may not have ->usage count > 0. The race window is between css_task_iter_next() invocations when css_set_lock is released and we may arrive at a new ->task_pos. The iterator should not attempt to resurrect tasks whose ->usage count dropped to zero. (When that happens, __put_task_struct_rcu_cb() is already imminent and the returned task_struct would could be used after free.) As for the fix, we cannot simply check the signal->live count of a task on the dying list because that won't distinguish regular zombies waiting to be reaped from RCU remnant tasks that are going to be free'd. Therefore add an extra check to rule out ->usage==0 tasks from any iteration. The repeat: loop in css_task_iter_advance() doesn't consider ->usage count, so add a new loop to css_task_iter_next() to skip de-used tasks on the dying_list. Rough illustration of the possible race R (reader of cgroup.procs) T (thread) L (group leader) --------------------------------- -------------------------------- -------------------------------- L exits, signal->live > 0 cgroup_task_dead(L) css_set_skip_task_iters() // skips only cset->tasks list_add_tail(&L->cg_list, &cset->dying_tasks) css_task_iter_next() take css_set_lock css_task_iter_advance() leader && signal->live != 0 => it->task_pos = &L->cg_list release css_set_lock T exits --signal->live == 0 cgroup_task_dead(T) // css_set_lock release_task(T) cgroup_task_release(T) release_task(L) // zap_leader cgroup_task_release(L) put_task_struct_rcu_user(L) ...RCU... put_task_struct(L) L->usage = 0 /* L still on dying_tasks */ ...RCU... __put_task_struct(L) css_task_iter_next() // another iteration take css_set_lock it->task_pos = &L->cg_list get_task_struct(L) => addition on 0 drop css_set_lock cgroup_task_free(L) css_set_skip_task_iters() // dying skip comes too late free_task(L) cgroup_procs_show() task_pid_vnr(L)•CVE-2026-98163