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

From: Greg Kroah-Hartman <[email-masked]>

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.

The Linux kernel CVE team has assigned CVE-2023-52603 to this issue.

Affected and fixed versions
===========================

	Fixed in 4.19.307 with commit e30b52a2ea3d
	Fixed in 5.4.269 with commit fd3486a89377
	Fixed in 5.10.210 with commit 7aa33854477d
	Fixed in 5.15.149 with commit e4ce01c25ccb
	Fixed in 6.1.77 with commit e4cbc857d75d
	Fixed in 6.6.16 with commit edff092a5926
	Fixed in 6.7.4 with commit 6e2902ecc77e
	Fixed in 6.8 with commit 27e56f59bab5

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-52603
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/jfs/jfs_dtree.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/e30b52a2ea3d1e0aaee68096957cf90a2f4ec5af
	https://git.kernel.org/stable/c/fd3486a893778770557649fe28afa5e463d4ed07
	https://git.kernel.org/stable/c/7aa33854477d9c346f5560a1a1fcb3fe7783e2a8
	https://git.kernel.org/stable/c/e4ce01c25ccbea02a09a5291c21749b1fc358e39
	https://git.kernel.org/stable/c/e4cbc857d75d4e22a1f75446e7480b1f305d8d60
	https://git.kernel.org/stable/c/edff092a59260bf0b0a2eba219cb3da6372c2f9f
	https://git.kernel.org/stable/c/6e2902ecc77e9760a9fc447f56d598383e2372d2
	https://git.kernel.org/stable/c/27e56f59bab5ddafbcfe69ad7a4a6ea1279c1b16