syzbot

loop0: detected capacity change from 0 to 32768
BUG at fs/jfs/jfs_dmap.c:3051 assert(n < 4)
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kernel BUG at fs/jfs/jfs_dmap.c:3051!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4323 Comm: syz.0.17 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:3051
Code: fe e9 51 ff ff ff e8 28 9a ad fe 48 c7 c7 c0 1e 42 8a 48 c7 c6 40 1c 42 8a ba eb 0b 00 00 48 c7 c1 c0 29 42 8a e8 f9 3c cd 06 <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec
RSP: 0018:ffffc90002fef278 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: b6ad4fd8dde3f300
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffed10172067b0
R10: ffffed10172067b0 R11: 1ffff110172067af R12: 0000000000000007
R13: 0000000000000060 R14: 000000000000005d R15: 0000000000000155
FS:  000055557afce500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31363fff CR3: 000000007db99000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dbAllocDmapLev+0x61/0x3c0 fs/jfs/jfs_dmap.c:2037
 dbAlloc+0x988/0xb90 fs/jfs/jfs_dmap.c:844
 extBalloc fs/jfs/jfs_extent.c:523 [inline]
 extAlloc+0x4d2/0xf30 fs/jfs/jfs_extent.c:125
 jfs_get_block+0x343/0xab0 fs/jfs/inode.c:264
 get_more_blocks fs/direct-io.c:673 [inline]
 do_direct_IO fs/direct-io.c:959 [inline]
 do_blockdev_direct_IO fs/direct-io.c:1276 [inline]
 __blockdev_direct_IO+0x146d/0x3c90 fs/direct-io.c:1368
 blockdev_direct_IO include/linux/fs.h:3345 [inline]
 jfs_direct_IO+0x119/0x220 fs/jfs/inode.c:349
 generic_file_direct_write+0x22c/0x490 mm/filemap.c:3687
 __generic_file_write_iter+0x2b1/0x4e0 mm/filemap.c:3869
 generic_file_write_iter+0xa6/0x1b0 mm/filemap.c:3944
 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
 do_iter_write+0x205/0x7b0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x204/0x340 fs/read_write.c:1025
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f13647ed749
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:00007ffec3418328 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f1364a43fa0 RCX: 00007f13647ed749
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007f1364871f91 R08: 0000000000000000 R09: 0000000000000003
R10: 0000000000002000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1364a43fa0 R14: 00007f1364a43fa0 R15: 0000000000000006
 </TASK>
Modules linked in:
---[ end trace c89b948366d4fe65 ]---
RIP: 0010:dbFindLeaf+0x517/0x520 fs/jfs/jfs_dmap.c:3051
Code: fe e9 51 ff ff ff e8 28 9a ad fe 48 c7 c7 c0 1e 42 8a 48 c7 c6 40 1c 42 8a ba eb 0b 00 00 48 c7 c1 c0 29 42 8a e8 f9 3c cd 06 <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec
RSP: 0018:ffffc90002fef278 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: b6ad4fd8dde3f300
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffed10172067b0
R10: ffffed10172067b0 R11: 1ffff110172067af R12: 0000000000000007
R13: 0000000000000060 R14: 000000000000005d R15: 0000000000000155
FS:  000055557afce500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31363fff CR3: 000000007db99000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400