[v6.1] possible deadlock in f2fs_add_inline_entry

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syzbot

unread,
Jul 23, 2023, 10:27:50 AM7/23/23
to syzkaller...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 75389113731b Linux 6.1.40
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16a4e081a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=9027f9f0abc1e82f
dashboard link: https://syzkaller.appspot.com/bug?extid=a31766fcc0092ed1bc13
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8579f6cd3c5c/disk-75389113.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cf95e75287e2/vmlinux-75389113.xz
kernel image: https://storage.googleapis.com/syzbot-assets/479ef4915330/bzImage-75389113.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a31766...@syzkaller.appspotmail.com

loop5: detected capacity change from 0 to 40427
F2FS-fs (loop5): Found nat_bits in checkpoint
F2FS-fs (loop5): Mounted with checkpoint version = 48b305e5
======================================================
WARNING: possible circular locking dependency detected
6.1.40-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/8772 is trying to acquire lock:
ffff888074584c68 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
ffff888074584c68 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645

but task is already holding lock:
ffff888074584618 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
ffff888074584618 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_add_dentry+0x9b/0x1e0 fs/f2fs/dir.c:814

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&fi->i_xattr_sem){.+.+}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_read+0x43/0x2e0 kernel/locking/rwsem.c:1520
f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
f2fs_getxattr+0xb4/0x1460 fs/f2fs/xattr.c:531
__f2fs_get_acl+0x52/0x8a0 fs/f2fs/acl.c:179
f2fs_acl_create fs/f2fs/acl.c:375 [inline]
f2fs_init_acl+0xd3/0x960 fs/f2fs/acl.c:418
f2fs_init_inode_metadata+0xaa0/0x11d0 fs/f2fs/dir.c:587
f2fs_add_regular_entry+0x866/0xe00 fs/f2fs/dir.c:771
f2fs_add_dentry+0xf3/0x1e0 fs/f2fs/dir.c:819
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_create+0x749/0xa10 fs/f2fs/namei.c:367
lookup_open fs/namei.c:3413 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x12f1/0x2e60 fs/namei.c:3711
do_filp_open+0x230/0x480 fs/namei.c:3741
do_sys_openat2+0x13b/0x500 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_open fs/open.c:1342 [inline]
__se_sys_open fs/open.c:1338 [inline]
__x64_sys_open+0x221/0x270 fs/open.c:1338
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&fi->i_sem){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573
f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645
f2fs_add_dentry+0xb6/0x1e0 fs/f2fs/dir.c:815
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_create+0x749/0xa10 fs/f2fs/namei.c:367
vfs_create+0x306/0x490 fs/namei.c:3115
do_mknodat+0x3f5/0x690 fs/namei.c:3965
__do_sys_mknodat fs/namei.c:3993 [inline]
__se_sys_mknodat fs/namei.c:3990 [inline]
__x64_sys_mknodat+0xa5/0xc0 fs/namei.c:3990
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&fi->i_xattr_sem);
lock(&fi->i_sem);
lock(&fi->i_xattr_sem);
lock(&fi->i_sem);

*** DEADLOCK ***

4 locks held by syz-executor.5/8772:
#0: ffff888148726460 (sb_writers#20){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
#1: ffff888074583fa8 (&type->i_mutex_dir_key#13/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#1: ffff888074583fa8 (&type->i_mutex_dir_key#13/1){+.+.}-{3:3}, at: filename_create+0x256/0x530 fs/namei.c:3807
#2: ffff88807eca43b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
#2: ffff88807eca43b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_lock_op fs/f2fs/f2fs.h:2197 [inline]
#2: ffff88807eca43b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_create+0x67e/0xa10 fs/f2fs/namei.c:366
#3: ffff888074584618 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
#3: ffff888074584618 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_add_dentry+0x9b/0x1e0 fs/f2fs/dir.c:814

stack backtrace:
CPU: 1 PID: 8772 Comm: syz-executor.5 Not tainted 6.1.40-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573
f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645
f2fs_add_dentry+0xb6/0x1e0 fs/f2fs/dir.c:815
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_create+0x749/0xa10 fs/f2fs/namei.c:367
vfs_create+0x306/0x490 fs/namei.c:3115
do_mknodat+0x3f5/0x690 fs/namei.c:3965
__do_sys_mknodat fs/namei.c:3993 [inline]
__se_sys_mknodat fs/namei.c:3990 [inline]
__x64_sys_mknodat+0xa5/0xc0 fs/namei.c:3990
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f3a5c07cb29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3a5cd280c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000103
RAX: ffffffffffffffda RBX: 00007f3a5c19bf80 RCX: 00007f3a5c07cb29
RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000004
RBP: 00007f3a5c0c847a R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000070a R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f3a5c19bf80 R15: 00007fff1b6de498
</TASK>


---
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syzbot

unread,
Jul 28, 2023, 5:27:45 PM7/28/23
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: d2a6dc4eaf6d Linux 6.1.42
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=135a1bd9a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=54d239cfb343e1e3
dashboard link: https://syzkaller.appspot.com/bug?extid=a31766fcc0092ed1bc13
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c71945a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166af381a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/48a245e1f181/disk-d2a6dc4e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/36fe96f5b416/vmlinux-d2a6dc4e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d53f0286f35a/bzImage-d2a6dc4e.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1270162e3c84/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a31766...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 40427
F2FS-fs (loop0): Found nat_bits in checkpoint
F2FS-fs (loop0): Mounted with checkpoint version = 48b305e5
======================================================
WARNING: possible circular locking dependency detected
6.1.42-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor166/3540 is trying to acquire lock:
ffff8880719116f8 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
ffff8880719116f8 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645

but task is already holding lock:
ffff8880719107c0 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
ffff8880719107c0 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_add_dentry+0x9b/0x1e0 fs/f2fs/dir.c:814

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&fi->i_xattr_sem){.+.+}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_read+0x43/0x2e0 kernel/locking/rwsem.c:1520
f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
f2fs_getxattr+0xb4/0x1460 fs/f2fs/xattr.c:531
__f2fs_get_acl+0x52/0x8a0 fs/f2fs/acl.c:179
f2fs_acl_create fs/f2fs/acl.c:375 [inline]
f2fs_init_acl+0xd3/0x960 fs/f2fs/acl.c:418
f2fs_init_inode_metadata+0xaa0/0x11d0 fs/f2fs/dir.c:587
f2fs_add_regular_entry+0x866/0xe00 fs/f2fs/dir.c:771
f2fs_add_dentry+0xf3/0x1e0 fs/f2fs/dir.c:819
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_mkdir+0x2f1/0x520 fs/f2fs/namei.c:771
vfs_mkdir+0x3b6/0x590 fs/namei.c:4036
do_mkdirat+0x260/0x520 fs/namei.c:4061
__do_sys_mkdir fs/namei.c:4081 [inline]
__se_sys_mkdir fs/namei.c:4079 [inline]
__x64_sys_mkdir+0x6a/0x80 fs/namei.c:4079
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&fi->i_sem){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573
f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645
f2fs_add_dentry+0xb6/0x1e0 fs/f2fs/dir.c:815
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_mkdir+0x2f1/0x520 fs/f2fs/namei.c:771
vfs_mkdir+0x3b6/0x590 fs/namei.c:4036
ovl_do_mkdir fs/overlayfs/overlayfs.h:186 [inline]
ovl_mkdir_real+0xcf/0x2c0 fs/overlayfs/dir.c:146
ovl_workdir_create+0x449/0x9d0 fs/overlayfs/super.c:799
ovl_make_workdir fs/overlayfs/super.c:1389 [inline]
ovl_get_workdir+0x3b7/0x17b0 fs/overlayfs/super.c:1539
ovl_fill_super+0x1b85/0x2a20 fs/overlayfs/super.c:2095
mount_nodev+0x52/0xe0 fs/super.c:1469
legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1553
do_new_mount+0x28b/0xae0 fs/namespace.c:3040
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&fi->i_xattr_sem);
lock(&fi->i_sem);
lock(&fi->i_xattr_sem);
lock(&fi->i_sem);

*** DEADLOCK ***

5 locks held by syz-executor166/3540:
#0: ffff88807b4460e0 (&type->s_umount_key#42/1){+.+.}-{3:3}, at: alloc_super+0x217/0x930 fs/super.c:228
#1: ffff88807acd8460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
#2: ffff888071910150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#2: ffff888071910150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: ovl_workdir_create+0x159/0x9d0 fs/overlayfs/super.c:771
#3: ffff8880761ec3b0 (&sbi->cp_rwsem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
#3: ffff8880761ec3b0 (&sbi->cp_rwsem){.+.+}-{3:3}, at: f2fs_lock_op fs/f2fs/f2fs.h:2197 [inline]
#3: ffff8880761ec3b0 (&sbi->cp_rwsem){.+.+}-{3:3}, at: f2fs_mkdir+0x221/0x520 fs/f2fs/namei.c:770
#4: ffff8880719107c0 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
#4: ffff8880719107c0 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_add_dentry+0x9b/0x1e0 fs/f2fs/dir.c:814

stack backtrace:
CPU: 1 PID: 3540 Comm: syz-executor166 Not tainted 6.1.42-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573
f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645
f2fs_add_dentry+0xb6/0x1e0 fs/f2fs/dir.c:815
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_mkdir+0x2f1/0x520 fs/f2fs/namei.c:771
vfs_mkdir+0x3b6/0x590 fs/namei.c:4036
ovl_do_mkdir fs/overlayfs/overlayfs.h:186 [inline]
ovl_mkdir_real+0xcf/0x2c0 fs/overlayfs/dir.c:146
ovl_workdir_create+0x449/0x9d0 fs/overlayfs/super.c:799
ovl_make_workdir fs/overlayfs/super.c:1389 [inline]
ovl_get_workdir+0x3b7/0x17b0 fs/overlayfs/super.c:1539
ovl_fill_super+0x1b85/0x2a20 fs/overlayfs/super.c:2095
mount_nodev+0x52/0xe0 fs/super.c:1469
legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1553
do_new_mount+0x28b/0xae0 fs/namespace.c:3040
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6912cc27b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 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:00007ffc2c9753c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f6912cc27b9
RDX: 00000000200001c0 RSI: 0000000020000180 RDI: 0000000000000000
RBP: 00007f6912d3a610 R08: 0000000020000300 R09: 0000000000000000


---
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