| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <6947c537.050a0220.1b4e0c.0028.GAE@google.com>
Date: Sun, 21 Dec 2025 02:00:23 -0800
From: syzbot <syzbot+212e8f62790f8e0bc63b@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: Re: [syzbot] [ext4?] possible deadlock in ext4_evict_inode (5)
syzbot has found a reproducer for the following issue on:
HEAD commit: cc3aa43b44bd Add linux-next specific files for 20251219
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16240584580000
kernel config: https://syzkaller.appspot.com/x/.config?x=da1bc82c6189c463
dashboard link: https://syzkaller.appspot.com/bug?extid=212e8f62790f8e0bc63b
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113b83c2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17785db4580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/30bf539e6f28/disk-cc3aa43b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0e2f8b08e342/vmlinux-cc3aa43b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec7ee6ece11f/bzImage-cc3aa43b.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/6d38ae5229b4/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=11ec9392580000)
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/e5fc772dada1/mount_1.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=163b83c2580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+212e8f62790f8e0bc63b@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.192/6440 is trying to acquire lock:
ffff88807d9c8610 (sb_internal){.+.+}-{0:0}, at: percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
ffff88807d9c8610 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs/super.h:19 [inline]
ffff88807d9c8610 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs/super.h:177 [inline]
ffff88807d9c8610 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x26f/0xe60 fs/ext4/inode.c:214
but task is already holding lock:
ffff88802a6a8b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1832 [inline]
ffff88802a6a8b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x2f3/0x1010 fs/ext4/migrate.c:438
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}:
percpu_down_read_internal+0x48/0x1c0 include/linux/percpu-rwsem.h:53
percpu_down_read include/linux/percpu-rwsem.h:77 [inline]
ext4_writepages_down_read fs/ext4/ext4.h:1820 [inline]
ext4_writepages+0x1ca/0x350 fs/ext4/inode.c:3025
do_writepages+0x32e/0x550 mm/page-writeback.c:2598
__writeback_single_inode+0x133/0x1240 fs/fs-writeback.c:1737
writeback_single_inode+0x493/0xc70 fs/fs-writeback.c:1858
write_inode_now+0x160/0x1d0 fs/fs-writeback.c:2924
iput_final fs/inode.c:1941 [inline]
iput+0xa77/0x1030 fs/inode.c:2003
ext4_xattr_block_set+0x1fce/0x2ac0 fs/ext4/xattr.c:2203
ext4_xattr_move_to_block fs/ext4/xattr.c:2668 [inline]
ext4_xattr_make_inode_space fs/ext4/xattr.c:2743 [inline]
ext4_expand_extra_isize_ea+0x12da/0x1ea0 fs/ext4/xattr.c:2831
__ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6349
ext4_try_to_expand_extra_isize fs/ext4/inode.c:6392 [inline]
__ext4_mark_inode_dirty+0x45c/0x6e0 fs/ext4/inode.c:6470
ext4_evict_inode+0x79c/0xe60 fs/ext4/inode.c:253
evict+0x5f4/0xae0 fs/inode.c:837
ext4_orphan_cleanup+0xc20/0x1460 fs/ext4/orphan.c:472
__ext4_fill_super fs/ext4/super.c:5658 [inline]
ext4_fill_super+0x58a1/0x6160 fs/ext4/super.c:5777
get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
vfs_get_tree+0x92/0x2a0 fs/super.c:1751
fc_mount fs/namespace.c:1199 [inline]
do_new_mount_fc fs/namespace.c:3636 [inline]
do_new_mount+0x302/0xa10 fs/namespace.c:3712
do_mount fs/namespace.c:4035 [inline]
__do_sys_mount fs/namespace.c:4224 [inline]
__se_sys_mount+0x313/0x410 fs/namespace.c:4201
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (sb_internal){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
percpu_down_read_internal+0x48/0x1c0 include/linux/percpu-rwsem.h:53
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_intwrite include/linux/fs/super.h:177 [inline]
ext4_evict_inode+0x26f/0xe60 fs/ext4/inode.c:214
evict+0x5f4/0xae0 fs/inode.c:837
ext4_ext_migrate+0xd23/0x1010 fs/ext4/migrate.c:588
__ext4_ioctl fs/ext4/ioctl.c:1688 [inline]
ext4_ioctl+0x204a/0x4760 fs/ext4/ioctl.c:1917
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sbi->s_writepages_rwsem);
lock(sb_internal);
lock(&sbi->s_writepages_rwsem);
rlock(sb_internal);
*** DEADLOCK ***
3 locks held by syz.4.192/6440:
#0: ffff88807d9c8420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:543
#1: ffff88805fc0b400 (&sb->s_type->i_mutex_key#11){++++}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
#1: ffff88805fc0b400 (&sb->s_type->i_mutex_key#11){++++}-{4:4}, at: __ext4_ioctl fs/ext4/ioctl.c:1687 [inline]
#1: ffff88805fc0b400 (&sb->s_type->i_mutex_key#11){++++}-{4:4}, at: ext4_ioctl+0x2042/0x4760 fs/ext4/ioctl.c:1917
#2: ffff88802a6a8b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1832 [inline]
#2: ffff88802a6a8b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x2f3/0x1010 fs/ext4/migrate.c:438
stack backtrace:
CPU: 1 UID: 0 PID: 6440 Comm: syz.4.192 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
percpu_down_read_internal+0x48/0x1c0 include/linux/percpu-rwsem.h:53
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_intwrite include/linux/fs/super.h:177 [inline]
ext4_evict_inode+0x26f/0xe60 fs/ext4/inode.c:214
evict+0x5f4/0xae0 fs/inode.c:837
ext4_ext_migrate+0xd23/0x1010 fs/ext4/migrate.c:588
__ext4_ioctl fs/ext4/ioctl.c:1688 [inline]
ext4_ioctl+0x204a/0x4760 fs/ext4/ioctl.c:1917
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f273d38f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc40d3ab8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f273d5e5fa0 RCX: 00007f273d38f749
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000005
RBP: 00007f273d413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f273d5e5fa0 R14: 00007f273d5e5fa0 R15: 0000000000000002
</TASK>
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
Powered by blists - more mailing lists