syzbot


KASAN: use-after-free Read in nilfs_set_link

Status: fixed on 2024/08/28 13:04
Reported-by: syzbot+db8e288ddafa154c0a09@syzkaller.appspotmail.com
Fix commit: 7000b438dda9 nilfs2: fix kernel bug on rename operation of broken directory
First crash: 126d, last: 126d
Fix bisection: fixed by (bisect log) :
commit 7000b438dda9d0f41a956fc9bffed92d2eb6be0d
Author: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Date: Fri Jun 28 16:51:07 2024 +0000

  nilfs2: fix kernel bug on rename operation of broken directory

  
Bug presence (1)
Date Name Commit Repro Result
2024/07/19 upstream (ToT) 720261cfc732 C Didn't crash
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in nilfs_set_link nilfs C inconclusive done 3 318d 314d 0/28 auto-obsoleted due to no activity on 2024/04/16 20:38
linux-6.1 KASAN: use-after-free Read in nilfs_set_link 1 126d 126d 0/3 auto-obsoleted due to no activity on 2024/10/26 08:47

Sample crash report:
loop0: detected capacity change from 0 to 4096
==================================================================
BUG: KASAN: use-after-free in nilfs_set_link+0x397/0x530 fs/nilfs2/dir.c:420
Read of size 2 at addr ffff88807acc8008 by task syz-executor354/3502

CPU: 0 PID: 3502 Comm: syz-executor354 Not tainted 5.15.162-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_address_description+0x63/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
 nilfs_set_link+0x397/0x530 fs/nilfs2/dir.c:420
 nilfs_rename+0x844/0xb80 fs/nilfs2/namei.c:414
 vfs_rename+0xd32/0x10f0 fs/namei.c:4832
 do_renameat2+0xe0f/0x1700 fs/namei.c:4985
 __do_sys_renameat2 fs/namei.c:5018 [inline]
 __se_sys_renameat2 fs/namei.c:5015 [inline]
 __x64_sys_renameat2+0xce/0xe0 fs/namei.c:5015
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3109bb71e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff4ea4d1f8 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f3109bb71e9
RDX: 0000000000000005 RSI: 00000000200001c0 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007fff4ea4d230
R10: 0000000020000200 R11: 0000000000000246 R12: 00007fff4ea4d21c
R13: 0000000000000001 R14: 431bde82d7b634db R15: 00007fff4ea4d250
 </TASK>

The buggy address belongs to the page:
page:ffffea0001eb3200 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x7acc8
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001eb02c8 ffffea0002ff9688 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100cca(GFP_HIGHUSER_MOVABLE), pid 3499, ts 41030921720, free_ts 41255446881
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x322a/0x33c0 mm/page_alloc.c:4159
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5423
 alloc_pages_vma+0x39a/0x800 mm/mempolicy.c:2146
 shmem_alloc_page mm/shmem.c:1586 [inline]
 shmem_alloc_and_acct_page+0x4d1/0xd10 mm/shmem.c:1611
 shmem_getpage_gfp+0x17b1/0x3190 mm/shmem.c:1906
 shmem_getpage mm/shmem.c:151 [inline]
 shmem_write_begin+0xce/0x1a0 mm/shmem.c:2477
 generic_perform_write+0x2bf/0x5b0 mm/filemap.c:3785
 __generic_file_write_iter+0x243/0x4f0 mm/filemap.c:3912
 generic_file_write_iter+0xa7/0x1b0 mm/filemap.c:3944
 call_write_iter include/linux/fs.h:2172 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0xacf/0xe50 fs/read_write.c:594
 ksys_write+0x1a2/0x2c0 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page_list+0x1f7/0x8e0 mm/page_alloc.c:3433
 release_pages+0x1bb9/0x1f40 mm/swap.c:963
 __pagevec_release+0x80/0xf0 mm/swap.c:983
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x67a/0x1b50 mm/shmem.c:964
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x21b/0xa00 mm/shmem.c:1145
 evict+0x2a4/0x620 fs/inode.c:587
 __dentry_kill+0x436/0x650 fs/dcache.c:582
 dentry_kill+0xbb/0x290
 dput+0xd8/0x1a0 fs/dcache.c:889
 __fput+0x5ec/0x890 fs/file_table.c:288
 task_work_run+0x129/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff88807acc7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807acc7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807acc8000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff88807acc8080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807acc8100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/18 06:27 linux-5.15.y f45bea23c39c 0f902625 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan KASAN: use-after-free Read in nilfs_set_link
* Struck through repros no longer work on HEAD.