CVE-2022-49983

Published Jun 18, 2025

Last updated 2 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: udmabuf: Set the DMA mask for the udmabuf device (v2) If the DMA mask is not set explicitly, the following warning occurs when the userspace tries to access the dma-buf via the CPU as reported by syzbot here: WARNING: CPU: 1 PID: 3595 at kernel/dma/mapping.c:188 __dma_map_sg_attrs+0x181/0x1f0 kernel/dma/mapping.c:188 Modules linked in: CPU: 0 PID: 3595 Comm: syz-executor249 Not tainted 5.17.0-rc2-syzkaller-00316-g0457e5153e0e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__dma_map_sg_attrs+0x181/0x1f0 kernel/dma/mapping.c:188 Code: 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 71 4c 8b 3d c0 83 b5 0d e9 db fe ff ff e8 b6 0f 13 00 0f 0b e8 af 0f 13 00 <0f> 0b 45 31 e4 e9 54 ff ff ff e8 a0 0f 13 00 49 8d 7f 50 48 b8 00 RSP: 0018:ffffc90002a07d68 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88807e25e2c0 RSI: ffffffff81649e91 RDI: ffff88801b848408 RBP: ffff88801b848000 R08: 0000000000000002 R09: ffff88801d86c74f R10: ffffffff81649d72 R11: 0000000000000001 R12: 0000000000000002 R13: ffff88801d86c680 R14: 0000000000000001 R15: 0000000000000000 FS: 0000555556e30300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200000cc CR3: 000000001d74a000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> dma_map_sgtable+0x70/0xf0 kernel/dma/mapping.c:264 get_sg_table.isra.0+0xe0/0x160 drivers/dma-buf/udmabuf.c:72 begin_cpu_udmabuf+0x130/0x1d0 drivers/dma-buf/udmabuf.c:126 dma_buf_begin_cpu_access+0xfd/0x1d0 drivers/dma-buf/dma-buf.c:1164 dma_buf_ioctl+0x259/0x2b0 drivers/dma-buf/dma-buf.c:363 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f62fcf530f9 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe3edab9b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f62fcf530f9 RDX: 0000000020000200 RSI: 0000000040086200 RDI: 0000000000000006 RBP: 00007f62fcf170e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f62fcf17170 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> v2: Dont't forget to deregister if DMA mask setup fails.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
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