CVE-2023-52599: Improper Validation of Array Index

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

jfs: fix array-index-out-of-bounds in diNewExt

[Syz report] UBSAN: array-index-out-of-bounds in fs/jfs/jfs_imap.c:2360:2 index -878706688 is out of range for type 'struct iagctl[128]' CPU: 1 PID: 5065 Comm: syz-executor282 Not tainted 6.7.0-rc4-syzkaller-00009-gbee0e7762ad2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023 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 diNewExt+0x3cf3/0x4000 fs/jfs/jfs_imap.c:2360 diAllocExt fs/jfs/jfs_imap.c:1949 [inline] diAllocAG+0xbe8/0x1e50 fs/jfs/jfs_imap.c:1666 diAlloc+0x1d3/0x1760 fs/jfs/jfs_imap.c:1587 ialloc+0x8f/0x900 fs/jfs/jfs_inode.c:56 jfs_mkdir+0x1c5/0xb90 fs/jfs/namei.c:225 vfs_mkdir+0x2f1/0x4b0 fs/namei.c:4106 do_mkdirat+0x264/0x3a0 fs/namei.c:4129 __do_sys_mkdir fs/namei.c:4149 [inline] __se_sys_mkdir fs/namei.c:4147 [inline] __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4147 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x45/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7fcb7e6a0b57 Code: ff ff 77 07 31 c0 c3 0f 1f 40 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 b8 53 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd83023038 EFLAGS: 00000286 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fcb7e6a0b57 RDX: 00000000000a1020 RSI: 00000000000001ff RDI: 0000000020000140 RBP: 0000000020000140 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000286 R12: 00007ffd830230d0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

[Analysis] When the agstart is too large, it can cause agno overflow.

[Fix] After obtaining agno, if the value is invalid, exit the subsequent process.

Modified the test from agno > MAXAG to agno >= MAXAG based on linux-next report by kernel test robot (Dan Carpenter).