BUG at fs/jfs/jfs_dmap.c:2983 assert(n < 4)
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kernel BUG at fs/jfs/jfs_dmap.c:2983!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7760 Comm: syz.4.340 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:dbFindLeaf+0x517/0x520 fs/jfs/jfs_dmap.c:2983
Code: fe e9 51 ff ff ff e8 68 ea 87 fe 48 c7 c7 a0 cd e3 8a 48 c7 c6 e0 ca e3 8a ba a7 0b 00 00 48 c7 c1 80 d8 e3 8a e8 e9 84 5e 07 <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec
RSP: 0018:ffffc9000da3eb90 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: 1fea004a8590bb00
RDX: ffffc9000d319000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000001 R08: ffffc9000da3e887 R09: 1ffff92001b47d10
R10: dffffc0000000000 R11: fffff52001b47d11 R12: 0000000000000000
R13: 000000000000015c R14: 0000000000000159 R15: 0000000000000555
FS:  00007f4adf6f56c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8d67faa450 CR3: 000000005f955000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 dbFindCtl+0x265/0x510 fs/jfs/jfs_dmap.c:1717
 dbAllocAny fs/jfs/jfs_dmap.c:1527 [inline]
 dbAlloc+0x5f9/0xba0 fs/jfs/jfs_dmap.c:878
 extBalloc fs/jfs/jfs_extent.c:326 [inline]
 extAlloc+0x4d6/0xf30 fs/jfs/jfs_extent.c:122
 jfs_get_block+0x347/0xab0 fs/jfs/inode.c:254
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 __block_write_begin fs/buffer.c:2173 [inline]
 block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
 jfs_write_begin+0x35/0x70 fs/jfs/inode.c:305
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
 __kernel_write_iter+0x274/0x670 fs/read_write.c:517
 dump_emit_page fs/coredump.c:957 [inline]
 dump_user_range+0x3f6/0x800 fs/coredump.c:984
 elf_core_dump+0x3114/0x36e0 fs/binfmt_elf.c:2184
 do_coredump+0x1755/0x2480 fs/coredump.c:833
 get_signal+0x1133/0x1400 kernel/signal.c:2888
 arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4ade78f749
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4adf6f50e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 00000000000000ca RBX: 00007f4ade9e6098 RCX: 00007f4ade78f749
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f4ade9e609c
RBP: 00007f4ade9e6090 R08: 0000000000745d1e R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ade9e6128 R14: 00007ffe0cd2c530 R15: 00007ffe0cd2c618
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbFindLeaf+0x517/0x520 fs/jfs/jfs_dmap.c:2983
Code: fe e9 51 ff ff ff e8 68 ea 87 fe 48 c7 c7 a0 cd e3 8a 48 c7 c6 e0 ca e3 8a ba a7 0b 00 00 48 c7 c1 80 d8 e3 8a e8 e9 84 5e 07 <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec
RSP: 0018:ffffc9000da3eb90 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: 1fea004a8590bb00
RDX: ffffc9000d319000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000001 R08: ffffc9000da3e887 R09: 1ffff92001b47d10
R10: dffffc0000000000 R11: fffff52001b47d11 R12: 0000000000000000
R13: 000000000000015c R14: 0000000000000159 R15: 0000000000000555
FS:  00007f4adf6f56c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7c99ac67b8 CR3: 000000005f955000 CR4: 00000000003506f0