CVE-2023-52603

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.

Bugs

• <https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2023-52603&gt;
• <https://bugzilla.suse.com/show_bug.cgi?id=1221066&gt;