syzbot


KASAN: slab-out-of-bounds Read in bch2_sb_clean_to_text

Status: fixed on 2024/06/05 13:52
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+c48865e11e7e893ec4ab@syzkaller.appspotmail.com
Fix commit: f39055220f6f bcachefs: Add missing validation for superblock section clean
First crash: 47d, last: 38d
Cause bisection: introduced by (bisect log) :
commit 03ef80b469d5d83530ce1ce15be78a40e5300f9b
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sat Sep 23 22:41:51 2023 +0000

  bcachefs: Ignore unknown mount options

Crash: KASAN: slab-out-of-bounds Read in bch2_sb_clean_to_text (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH] bcachefs: fix oob in bch2_sb_clean_to_text 10 (10) 2024/05/08 01:28
[syzbot] [bcachefs?] KASAN: slab-out-of-bounds Read in bch2_sb_clean_to_text 1 (4) 2024/05/07 02:32
Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/05/07 02:13 17m eadavis@qq.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5eb4573ea63d OK log

Sample crash report:
loop0: detected capacity change from 0 to 32768
==================================================================
BUG: KASAN: slab-out-of-bounds in bch2_sb_clean_to_text+0x17f/0x230 fs/bcachefs/sb-clean.c:298
Read of size 1 at addr ffff888023ef6004 by task syz-executor493/5073

CPU: 0 PID: 5073 Comm: syz-executor493 Not tainted 6.9.0-rc6-syzkaller-00234-g7367539ad4b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 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_sb_clean_to_text+0x17f/0x230 fs/bcachefs/sb-clean.c:298
 bch2_sb_field_validate+0x1f7/0x2d0 fs/bcachefs/super-io.c:1211
 bch2_sb_validate+0xa79/0xe10 fs/bcachefs/super-io.c:468
 __bch2_read_super+0xc9a/0x1460 fs/bcachefs/super-io.c:822
 bch2_fs_open+0x246/0xdf0 fs/bcachefs/super.c:2049
 bch2_mount+0x71d/0x1320 fs/bcachefs/fs.c:1903
 legacy_get_tree+0xee/0x190 fs/fs_context.c:662
 vfs_get_tree+0x90/0x2a0 fs/super.c:1779
 do_new_mount+0x2be/0xb40 fs/namespace.c:3352
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2a126618fa
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:00007ffe44de6bb8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe44de6bd0 RCX: 00007f2a126618fa
RDX: 0000000020011a00 RSI: 0000000020011a40 RDI: 00007ffe44de6bd0
RBP: 0000000000000004 R08: 00007ffe44de6c10 R09: 00000000000119fe
R10: 0000000003004000 R11: 0000000000000282 R12: 0000000003004000
R13: 00007ffe44de6c10 R14: 0000000000000003 R15: 0000000001000000
 </TASK>

Allocated by task 5073:
 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:3966 [inline]
 __kmalloc_node_track_caller+0x24e/0x4e0 mm/slub.c:3986
 __do_krealloc mm/slab_common.c:1192 [inline]
 krealloc+0x7d/0x120 mm/slab_common.c:1225
 bch2_sb_realloc+0x2fc/0x660 fs/bcachefs/super-io.c:189
 read_one_super+0x7d7/0x3a10 fs/bcachefs/super-io.c:659
 __bch2_read_super+0x65a/0x1460 fs/bcachefs/super-io.c:750
 bch2_fs_open+0x246/0xdf0 fs/bcachefs/super.c:2049
 bch2_mount+0x71d/0x1320 fs/bcachefs/fs.c:1903
 legacy_get_tree+0xee/0x190 fs/fs_context.c:662
 vfs_get_tree+0x90/0x2a0 fs/super.c:1779
 do_new_mount+0x2be/0xb40 fs/namespace.c:3352
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888023ef4000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4 bytes to the right of
 allocated 8192-byte region [ffff888023ef4000, ffff888023ef6000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23ef0
head: order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888015042280 ffffea0000910a00 0000000000000005
raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000
head: 00fff00000000840 ffff888015042280 ffffea0000910a00 0000000000000005
head: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000
head: 00fff00000000003 ffffea00008fbc01 ffffea00008fbc48 00000000ffffffff
head: 0000000800000000 0000000000000000 00000000ffffffff 0000000000000000
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 4736, tgid 1480517225 (sh), ts 4736, free_ts 31493460772
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
 prep_new_page mm/page_alloc.c:1541 [inline]
 get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
 __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page+0x5f/0x160 mm/slub.c:2175
 allocate_slab mm/slub.c:2338 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2391
 ___slab_alloc+0xc73/0x1260 mm/slub.c:3525
 __slab_alloc mm/slub.c:3610 [inline]
 __slab_alloc_node mm/slub.c:3663 [inline]
 slab_alloc_node mm/slub.c:3835 [inline]
 kmalloc_trace+0x269/0x360 mm/slub.c:3992
 kmalloc include/linux/slab.h:628 [inline]
 kzalloc include/linux/slab.h:749 [inline]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0x11ce/0x2050 security/tomoyo/audit.c:264
 tomoyo_supervisor+0x38a/0x11f0 security/tomoyo/common.c:2089
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x178/0x210 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x1384/0x1cf0 security/tomoyo/domain.c:878
 tomoyo_bprm_check_security+0x115/0x180 security/tomoyo/tomoyo.c:102
 security_bprm_check+0x65/0x90 security/security.c:1191
 search_binary_handler fs/exec.c:1766 [inline]
 exec_binprm fs/exec.c:1820 [inline]
 bprm_execve+0xa56/0x17c0 fs/exec.c:1872
 do_execveat_common+0x553/0x700 fs/exec.c:1979
 do_execve fs/exec.c:2053 [inline]
 __do_sys_execve fs/exec.c:2129 [inline]
 __se_sys_execve fs/exec.c:2124 [inline]
 __x64_sys_execve+0x92/0xb0 fs/exec.c:2124
page last free pid 4734 tgid 4734 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1141 [inline]
 free_unref_page_prepare+0x97b/0xaa0 mm/page_alloc.c:2347
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
 discard_slab mm/slub.c:2437 [inline]
 __put_partials+0xeb/0x130 mm/slub.c:2906
 put_cpu_partial+0x17c/0x250 mm/slub.c:2981
 __slab_free+0x2ea/0x3d0 mm/slub.c:4151
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x5e/0xc0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3798 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmem_cache_alloc+0x174/0x340 mm/slub.c:3852
 getname_flags+0xbd/0x4f0 fs/namei.c:139
 do_sys_openat2+0xd2/0x1d0 fs/open.c:1400
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1432
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888023ef5f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888023ef5f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888023ef6000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff888023ef6080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888023ef6100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/05 16:50 upstream 7367539ad4b0 610f2a54 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs KASAN: slab-out-of-bounds Read in bch2_sb_clean_to_text
2024/05/15 04:46 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci fda5695d692c fdb4c10c .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-gce-arm64 KASAN: slab-out-of-bounds Read in bch2_sb_clean_to_text
2024/05/05 16:29 upstream 7367539ad4b0 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Read in bch2_sb_clean_to_text
* Struck through repros no longer work on HEAD.