Re: [syzbot] [bcachefs?] KASAN: slab-out-of-bounds Write in bch2_dev_journal_init

[syzbot <syzbot+47ecc948aadfb2ab3efc@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Write in bch2_dev_journal_init

loop0: detected capacity change from 0 to 32768
==================================================================
BUG: KASAN: slab-out-of-bounds in bch2_dev_journal_init+0x8ea/0xcf0 fs/bcachefs/journal.c:1349
Write of size 8 at addr ffff88800e56e7b0 by task syz.0.15/5578

CPU: 0 UID: 0 PID: 5578 Comm: syz.0.15 Not tainted 6.11.0-rc3-syzkaller-00338-gc3f2d783a459-dirty #0
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 lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 bch2_dev_journal_init+0x8ea/0xcf0 fs/bcachefs/journal.c:1349
 __bch2_dev_attach_bdev+0x217/0x340 fs/bcachefs/super.c:1390
 bch2_dev_attach_bdev+0x2a8/0x6f0 fs/bcachefs/super.c:1420
 bch2_fs_open+0x97c/0xdf0 fs/bcachefs/super.c:2122
 bch2_fs_get_tree+0x731/0x1700 fs/bcachefs/fs.c:1933
 vfs_get_tree+0x90/0x2a0 fs/super.c:1800
 do_new_mount+0x2be/0xb40 fs/namespace.c:3472
 do_mount fs/namespace.c:3812 [inline]
 __do_sys_mount fs/namespace.c:4020 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3997
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fedc237b0ba
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 7e 1a 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fedc31b7e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fedc31b7ef0 RCX: 00007fedc237b0ba
RDX: 00000000200058c0 RSI: 0000000020005900 RDI: 00007fedc31b7eb0
RBP: 00000000200058c0 R08: 00007fedc31b7ef0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020005900
R13: 00007fedc31b7eb0 R14: 00000000000058ad R15: 0000000020005940
 </TASK>

Allocated by task 5578:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slub.c:4158 [inline]
 __kmalloc_noprof+0x1fc/0x400 mm/slub.c:4170
 kmalloc_noprof include/linux/slab.h:685 [inline]
 kmalloc_array_noprof include/linux/slab.h:726 [inline]
 bch2_dev_journal_init+0x77c/0xcf0 fs/bcachefs/journal.c:1339
 __bch2_dev_attach_bdev+0x217/0x340 fs/bcachefs/super.c:1390
 bch2_dev_attach_bdev+0x2a8/0x6f0 fs/bcachefs/super.c:1420
 bch2_fs_open+0x97c/0xdf0 fs/bcachefs/super.c:2122
 bch2_fs_get_tree+0x731/0x1700 fs/bcachefs/fs.c:1933
 vfs_get_tree+0x90/0x2a0 fs/super.c:1800
 do_new_mount+0x2be/0xb40 fs/namespace.c:3472
 do_mount fs/namespace.c:3812 [inline]
 __do_sys_mount fs/namespace.c:4020 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3997
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88800e56e780
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes to the right of
 allocated 48-byte region [ffff88800e56e780, ffff88800e56e7b0)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xe56e
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 00fff00000000000 ffff8880158418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080200020 00000001fdffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x152cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5138, tgid 5138 (syz-executor), ts 83628656409, free_ts 36738612732
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4695
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x5f/0x120 mm/slub.c:2321
 allocate_slab+0x5a/0x2f0 mm/slub.c:2484
 new_slab mm/slub.c:2537 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3723
 __slab_alloc+0x58/0xa0 mm/slub.c:3813
 __slab_alloc_node mm/slub.c:3866 [inline]
 slab_alloc_node mm/slub.c:4025 [inline]
 __kmalloc_cache_node_noprof+0x20c/0x300 mm/slub.c:4197
 kmalloc_node_noprof include/linux/slab.h:704 [inline]
 __get_vm_area_node+0x113/0x270 mm/vmalloc.c:3109
 __vmalloc_node_range_noprof+0x3c6/0x1400 mm/vmalloc.c:3794
 __vmalloc_node_noprof mm/vmalloc.c:3899 [inline]
 vzalloc_noprof+0x79/0x90 mm/vmalloc.c:3972
 alloc_counters+0xd7/0x740 net/ipv4/netfilter/ip_tables.c:799
 copy_entries_to_user net/ipv4/netfilter/arp_tables.c:681 [inline]
 get_entries net/ipv4/netfilter/arp_tables.c:867 [inline]
 do_arpt_get_ctl+0xe77/0x16a0 net/ipv4/netfilter/arp_tables.c:1461
 nf_getsockopt+0x299/0x2c0 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x222/0x2e0 net/ipv4/ip_sockglue.c:1777
 tcp_getsockopt+0x163/0x1c0 net/ipv4/tcp.c:4409
page last free pid 28 tgid 28 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2612
 __folio_put+0x2c8/0x440 mm/swap.c:128
 migrate_folio_move mm/migrate.c:1330 [inline]
 migrate_pages_batch+0x2a76/0x3560 mm/migrate.c:1818
 migrate_pages_sync mm/migrate.c:1884 [inline]
 migrate_pages+0x1f59/0x3460 mm/migrate.c:1993
 compact_zone+0x3404/0x4af0 mm/compaction.c:2671
 compact_node+0x2de/0x460 mm/compaction.c:2935
 kcompactd+0x788/0x1530 mm/compaction.c:3233
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff88800e56e680: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88800e56e700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88800e56e780: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff88800e56e800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88800e56e880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         c3f2d783 Merge tag 'mm-hotfixes-stable-2024-08-17-19-3..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=14bc03e5980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7229118d88b4a71b
dashboard link: https://syzkaller.appspot.com/bug?extid=47ecc948aadfb2ab3efc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=155d8b83980000