CVE-2023-53485

Published Oct 1, 2025

Last updated 3 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: fs: jfs: Fix UBSAN: array-index-out-of-bounds in dbAllocDmapLev Syzkaller reported the following issue: UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:1965:6 index -84 is out of range for type 's8[341]' (aka 'signed char[341]') CPU: 1 PID: 4995 Comm: syz-executor146 Not tainted 6.4.0-rc6-syzkaller-00037-gb6dad5178cea #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348 dbAllocDmapLev+0x3e5/0x430 fs/jfs/jfs_dmap.c:1965 dbAllocCtl+0x113/0x920 fs/jfs/jfs_dmap.c:1809 dbAllocAG+0x28f/0x10b0 fs/jfs/jfs_dmap.c:1350 dbAlloc+0x658/0xca0 fs/jfs/jfs_dmap.c:874 dtSplitUp fs/jfs/jfs_dtree.c:974 [inline] dtInsert+0xda7/0x6b00 fs/jfs/jfs_dtree.c:863 jfs_create+0x7b6/0xbb0 fs/jfs/namei.c:137 lookup_open fs/namei.c:3492 [inline] open_last_lookups fs/namei.c:3560 [inline] path_openat+0x13df/0x3170 fs/namei.c:3788 do_filp_open+0x234/0x490 fs/namei.c:3818 do_sys_openat2+0x13f/0x500 fs/open.c:1356 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1383 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f1f4e33f7e9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 90 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:00007ffc21129578 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1f4e33f7e9 RDX: 000000000000275a RSI: 0000000020000040 RDI: 00000000ffffff9c RBP: 00007f1f4e2ff080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1f4e2ff110 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> The bug occurs when the dbAllocDmapLev()function attempts to access dp->tree.stree[leafidx + LEAFIND] while the leafidx value is negative. To rectify this, the patch introduces a safeguard within the dbAllocDmapLev() function. A check has been added to verify if leafidx is negative. If it is, the function immediately returns an I/O error, preventing any further execution that could potentially cause harm. Tested via syzbot.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

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-129

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