CVE-2025-38227

Published Jul 4, 2025

Last updated 3 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: media: vidtv: Terminating the subsequent process of initialization failure syzbot reported a slab-use-after-free Read in vidtv_mux_init. [1] After PSI initialization fails, the si member is accessed again, resulting in this uaf. After si initialization fails, the subsequent process needs to be exited. [1] BUG: KASAN: slab-use-after-free in vidtv_mux_pid_ctx_init drivers/media/test-drivers/vidtv/vidtv_mux.c:78 [inline] BUG: KASAN: slab-use-after-free in vidtv_mux_init+0xac2/0xbe0 drivers/media/test-drivers/vidtv/vidtv_mux.c:524 Read of size 8 at addr ffff88802fa42acc by task syz.2.37/6059 CPU: 0 UID: 0 PID: 6059 Comm: syz.2.37 Not tainted 6.14.0-rc5-syzkaller #0 Hardware name: Google Compute Engine, BIOS Google 02/12/2025 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xd9/0x110 mm/kasan/report.c:634 vidtv_mux_pid_ctx_init drivers/media/test-drivers/vidtv/vidtv_mux.c:78 vidtv_mux_init+0xac2/0xbe0 drivers/media/test-drivers/vidtv/vidtv_mux.c:524 vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 vidtv_start_feed drivers/media/test-drivers/vidtv/vidtv_bridge.c:239 dmx_section_feed_start_filtering drivers/media/dvb-core/dvb_demux.c:973 dvb_dmxdev_feed_start drivers/media/dvb-core/dmxdev.c:508 [inline] dvb_dmxdev_feed_restart.isra.0 drivers/media/dvb-core/dmxdev.c:537 dvb_dmxdev_filter_stop+0x2b4/0x3a0 drivers/media/dvb-core/dmxdev.c:564 dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:840 [inline] dvb_demux_release+0x92/0x550 drivers/media/dvb-core/dmxdev.c:1246 __fput+0x3ff/0xb70 fs/file_table.c:464 task_work_run+0x14e/0x250 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xad8/0x2d70 kernel/exit.c:938 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087 __do_sys_exit_group kernel/exit.c:1098 [inline] __se_sys_exit_group kernel/exit.c:1096 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096 x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f871d58d169 Code: Unable to access opcode bytes at 0x7f871d58d13f. RSP: 002b:00007fff4b19a788 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f871d58d169 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fff4b19a7ec R08: 0000000b4b19a87f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000003 R13: 00000000000927c0 R14: 000000000001d553 R15: 00007fff4b19a840 </TASK> Allocated by task 6059: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 kmalloc_noprof include/linux/slab.h:901 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] vidtv_psi_pat_table_init drivers/media/test-drivers/vidtv/vidtv_psi.c:970 vidtv_channel_si_init drivers/media/test-drivers/vidtv/vidtv_channel.c:423 vidtv_mux_init drivers/media/test-drivers/vidtv/vidtv_mux.c:519 vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 vidtv_start_feed drivers/media/test-drivers/vidtv/vidtv_bridge.c:239 dmx_section_feed_start_filtering drivers/media/dvb-core/dvb_demux.c:973 dvb_dmxdev_feed_start drivers/media/dvb-core/dmxdev.c:508 [inline] dvb_dmxdev_feed_restart.isra.0 drivers/media/dvb-core/dmxdev.c:537 dvb_dmxdev_filter_stop+0x2b4/0x3a0 drivers/media/dvb-core/dmxdev.c:564 dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:840 [inline] dvb_demux_release+0x92/0x550 drivers/media/dvb-core/dmxdev.c:1246 __fput+0x3ff/0xb70 fs/file_tabl ---truncated---
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel, debian_linux

Risk scores

CVSS 3.1

Type
Primary
Base score
7.8
Impact score
5.9
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

nvd@nist.gov
CWE-416

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