[syzbot] [bcachefs?] KASAN: slab-out-of-bounds Read in bch2_sb_members_v1_to_text

[syzbot <syzbot+e577022d4fba380653be@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    b27cc623e01b Add linux-next specific files for 20250610
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11a1e9d4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=846e731334efc0f8
dashboard link: https://syzkaller.appspot.com/bug?extid=e577022d4fba380653be
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b2260c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1144cd70580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1c0c417339c8/disk-b27cc623.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fa29c0f3a1fa/vmlinux-b27cc623.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b902a80b6e7e/bzImage-b27cc623.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/9ddd2f474e69/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e577022d4fba380653be@syzkaller.appspotmail.com

WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
==================================================================
BUG: KASAN: slab-out-of-bounds in members_v1_get fs/bcachefs/sb-members.c:81 [inline]
BUG: KASAN: slab-out-of-bounds in bch2_sb_members_v1_to_text+0x1b2/0x2b0 fs/bcachefs/sb-members.c:334
Read of size 56 at addr ffff88803377dfd8 by task syz-executor978/5840

CPU: 1 UID: 0 PID: 5840 Comm: syz-executor978 Not tainted 6.16.0-rc1-next-20250610-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 members_v1_get fs/bcachefs/sb-members.c:81 [inline]
 bch2_sb_members_v1_to_text+0x1b2/0x2b0 fs/bcachefs/sb-members.c:334
 bch2_sb_field_validate+0x1c6/0x280 fs/bcachefs/super-io.c:1380
 bch2_sb_validate+0x14bd/0x1980 fs/bcachefs/super-io.c:552
 __bch2_read_super+0xba4/0x1040 fs/bcachefs/super-io.c:925
 bch2_fs_open+0x1fe/0x2570 fs/bcachefs/super.c:2382
 bch2_fs_get_tree+0x437/0x14f0 fs/bcachefs/fs.c:2473
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4410
 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: 0033:0x7f3ede35b93a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 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:00007ffebfe7f6d8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffebfe7f6f0 RCX: 00007f3ede35b93a
RDX: 00002000000003c0 RSI: 0000200000000080 RDI: 00007ffebfe7f6f0
RBP: 0000200000000080 R08: 00007ffebfe7f730 R09: 000000000000592e
R10: 0000000000808040 R11: 0000000000000282 R12: 00002000000003c0
R13: 00007ffebfe7f730 R14: 0000000000000003 R15: 0000000000808040
 </TASK>

Allocated by task 5840:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_node_track_caller_noprof+0x271/0x4e0 mm/slub.c:4347
 __do_krealloc mm/slub.c:4905 [inline]
 krealloc_noprof+0x124/0x340 mm/slub.c:4958
 bch2_sb_realloc+0x348/0x630 fs/bcachefs/super-io.c:222
 read_one_super+0x3a3/0x850 fs/bcachefs/super-io.c:759
 __bch2_read_super+0x6c6/0x1040 fs/bcachefs/super-io.c:851
 bch2_fs_open+0x1fe/0x2570 fs/bcachefs/super.c:2382
 bch2_fs_get_tree+0x437/0x14f0 fs/bcachefs/fs.c:2473
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4410
 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 ffff88803377c000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 8152 bytes inside of
 allocated 8192-byte region [ffff88803377c000, ffff88803377e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33778
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a442280 ffffea0000d03200 0000000000000005
raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a442280 ffffea0000d03200 0000000000000005
head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000cdde01 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 Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5495, tgid 5495 (sh), ts 57351029645, free_ts 57299723965
 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]
 __kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0x111f/0x1f70 security/tomoyo/audit.c:264
 tomoyo_supervisor+0x340/0x1480 security/tomoyo/common.c:2198
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x149/0x1e0 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x15cf/0x1aa0 security/tomoyo/domain.c:888
 tomoyo_bprm_check_security+0x11c/0x180 security/tomoyo/tomoyo.c:102
 security_bprm_check+0x89/0x270 security/security.c:1302
 search_binary_handler fs/exec.c:1655 [inline]
 exec_binprm fs/exec.c:1697 [inline]
 bprm_execve+0x8ee/0x1450 fs/exec.c:1749
 do_execveat_common+0x510/0x6a0 fs/exec.c:1855
 do_execve fs/exec.c:1929 [inline]
 __do_sys_execve fs/exec.c:2005 [inline]
 __se_sys_execve fs/exec.c:2000 [inline]
 __x64_sys_execve+0x94/0xb0 fs/exec.c:2000
page last free pid 5494 tgid 5494 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 discard_slab mm/slub.c:2717 [inline]
 __put_partials+0x161/0x1c0 mm/slub.c:3186
 put_cpu_partial+0x17c/0x250 mm/slub.c:3261
 __slab_free+0x2f7/0x400 mm/slub.c:4513
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
 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]
 __kmalloc_cache_noprof+0x1be/0x3d0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 tomoyo_print_header security/tomoyo/audit.c:156 [inline]
 tomoyo_init_log+0x183/0x1f70 security/tomoyo/audit.c:255
 tomoyo_supervisor+0x340/0x1480 security/tomoyo/common.c:2198
 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
 tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:587
 tomoyo_check_open_permission+0x24d/0x3b0 security/tomoyo/file.c:777
 security_file_open+0xb1/0x270 security/security.c:3114
 do_dentry_open+0x35e/0x1970 fs/open.c:941
 vfs_open+0x3b/0x340 fs/open.c:1094
 do_open fs/namei.c:3887 [inline]
 path_openat+0x2ee5/0x3830 fs/namei.c:4046

Memory state around the buggy address:
 ffff88803377df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88803377df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88803377e000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88803377e080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88803377e100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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