syzbot


KASAN: slab-out-of-bounds Read in dtReadFirst

Status: moderation: reported on 2025/07/02 05:37
Subsystems: jfs
[Documentation on labels]
Reported-by: syzbot+e8672e997d29f64e92d2@syzkaller.appspotmail.com
First crash: 6d04h, last: 6d04h
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 UBSAN: array-index-out-of-bounds in dtReadFirst origin:lts-only C error 23 57d 221d 0/3 upstream: reported C repro on 2024/11/25 10:09
upstream UBSAN: array-index-out-of-bounds in dtReadFirst jfs C error 200 201d 429d 28/29 fixed on 2024/12/16 09:50
linux-5.15 UBSAN: array-index-out-of-bounds in dtReadFirst origin:upstream C error 32 53d 431d 0/3 upstream: reported C repro on 2024/04/28 12:32
upstream UBSAN: array-index-out-of-bounds in dtReadFirst (2) jfs C error 119 66d 195d 28/29 fixed on 2025/06/10 16:19

Sample crash report:
loop0: detected capacity change from 0 to 32768
==================================================================
BUG: KASAN: slab-out-of-bounds in addressPXD fs/jfs/jfs_types.h:80 [inline]
BUG: KASAN: slab-out-of-bounds in dtReadFirst+0x502/0x930 fs/jfs/jfs_dtree.c:3120
Read of size 4 at addr ffff888044054028 by task syz.0.0/5318

CPU: 0 UID: 0 PID: 5318 Comm: syz.0.0 Not tainted 6.16.0-rc3-syzkaller-00233-g35e261cd95dd #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 addressPXD fs/jfs/jfs_types.h:80 [inline]
 dtReadFirst+0x502/0x930 fs/jfs/jfs_dtree.c:3120
 jfs_readdir+0x709/0x3ae0 fs/jfs/jfs_dtree.c:2832
 wrap_directory_iterator+0x93/0xe0 fs/readdir.c:65
 iterate_dir+0x5ac/0x770 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:410 [inline]
 __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5a5458e929
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:00007f5a554e0038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f5a547b5fa0 RCX: 00007f5a5458e929
RDX: 0000000000000099 RSI: 0000200000000400 RDI: 0000000000000007
RBP: 00007f5a54610b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5a547b5fa0 R15: 00007ffff1970c88
 </TASK>

Allocated by task 5318:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 kmem_cache_alloc_lru_noprof+0x1c6/0x3d0 mm/slub.c:4216
 jfs_alloc_inode+0x28/0x70 fs/jfs/super.c:105
 alloc_inode+0x6a/0x1b0 fs/inode.c:346
 new_inode+0x22/0x170 fs/inode.c:1145
 ialloc+0x4c/0x8f0 fs/jfs/jfs_inode.c:48
 jfs_create+0x18d/0xa80 fs/jfs/namei.c:92
 lookup_open fs/namei.c:3717 [inline]
 open_last_lookups fs/namei.c:3816 [inline]
 path_openat+0x14f1/0x3830 fs/namei.c:4052
 do_filp_open+0x1fa/0x410 fs/namei.c:4082
 do_sys_openat2+0x121/0x1c0 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1463
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888044053750
 which belongs to the cache jfs_ip of size 2232
The buggy address is located 32 bytes to the right of
 allocated 2232-byte region [ffff888044053750, ffff888044054008)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x44050
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888043224701
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff888032509b40 dead000000000122 0000000000000000
raw: 0000000000000000 00000000800d000d 00000000f5000000 ffff888043224701
head: 04fff00000000040 ffff888032509b40 dead000000000122 0000000000000000
head: 0000000000000000 00000000800d000d 00000000f5000000 ffff888043224701
head: 04fff00000000003 ffffea0001101401 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0xd2050(__GFP_RECLAIMABLE|__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5318, tgid 5317 (syz.0.0), ts 75506420002, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 kmem_cache_alloc_lru_noprof+0x288/0x3d0 mm/slub.c:4216
 jfs_alloc_inode+0x28/0x70 fs/jfs/super.c:105
 alloc_inode+0x6a/0x1b0 fs/inode.c:346
 new_inode+0x22/0x170 fs/inode.c:1145
 jfs_fill_super+0x569/0xd90 fs/jfs/super.c:511
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x92/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888044053f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888044053f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888044054000: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                  ^
 ffff888044054080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888044054100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/28 05:29 upstream 35e261cd95dd fc9d8ee5 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Read in dtReadFirst
* Struck through repros no longer work on HEAD.