CVE-2023-52603 UBSAN: array-index-out-of-bounds in dtSplitRoot

What is CVE-2023-52603?

CVE-2023-52603 is a high-severity memory corruption vulnerability in Linux kernel, published on 6 Mar 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

UBSAN: array-index-out-of-bounds in dtSplitRoot

Syzkaller reported the following issue:

oop0: detected capacity change from 0 to 32768

UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dtree.c:1971:9 index -2 is out of range for type 'struct dtslot [128]' CPU: 0 PID: 3613 Comm: syz-executor270 Not tainted 6.0.0-syzkaller-09423-g493ffd6605b2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:151 [inline] __ubsan_handle_out_of_bounds+0xdb/0x130 lib/ubsan.c:283 dtSplitRoot+0x8d8/0x1900 fs/jfs/jfs_dtree.c:1971 dtSplitUp fs/jfs/jfs_dtree.c:985 [inline] dtInsert+0x1189/0x6b80 fs/jfs/jfs_dtree.c:863 jfs_mkdir+0x757/0xb00 fs/jfs/namei.c:270 vfs_mkdir+0x3b3/0x590 fs/namei.c:4013 do_mkdirat+0x279/0x550 fs/namei.c:4038 __do_sys_mkdirat fs/namei.c:4053 [inline] __se_sys_mkdirat fs/namei.c:4051 [inline] __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4051 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fcdc0113fd9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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:00007ffeb8bc67d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcdc0113fd9 RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000003 RBP: 00007fcdc00d37a0 R08: 0000000000000000 R09: 00007fcdc00d37a0 R10: 00005555559a72c0 R11: 0000000000000246 R12: 00000000f8008000 R13: 0000000000000000 R14: 00083878000000f8 R15: 0000000000000000 </TASK>

The issue is caused when the value of fsi becomes less than -1. The check to break the loop when fsi value becomes -1 is present but syzbot was able to produce value less than -1 which cause the error. This patch simply add the change for the values less than 0.

The patch is tested via syzbot.

Weakness: CWE-129

Which versions are affected by CVE-2023-52603?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2023-52603?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2023-52603 being exploited?

There is no known exploitation of CVE-2023-52603 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2023-52603, DEBIAN-CVE-2023-52603, GHSA-pxxv-p7c4-h643, UBUNTU-CVE-2023-52603.