* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
@ 2025-09-24 0:28 ` Hillf Danton
2025-09-24 0:56 ` syzbot
2025-09-24 9:44 ` Edward Adam Davis
` (5 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Hillf Danton @ 2025-09-24 0:28 UTC (permalink / raw)
To: syzbot; +Cc: linux-kernel, syzkaller-bugs
> Date: Tue, 23 Sep 2025 15:59:37 -0700 [thread overview]
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: ce7f1a983b07 Add linux-next specific files for 20250923
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=118724e2580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
> dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
> 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=1376e27c580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136e78e2580000
#syz test
--- x/security/landlock/fs.c
+++ y/security/landlock/fs.c
@@ -1434,8 +1434,6 @@ static void hook_sb_delete(struct super_
spin_unlock(&inode->i_lock);
continue;
}
- /* Keeps a reference to this inode until the next loop walk. */
- __iget(inode);
spin_unlock(&inode->i_lock);
/*
@@ -1457,15 +1455,6 @@ static void hook_sb_delete(struct super_
* It is therefore not necessary to lock inode->i_lock.
*/
rcu_assign_pointer(landlock_inode(inode)->object, NULL);
- /*
- * At this point, we own the ihold() reference that was
- * originally set up by get_inode_object() and the
- * __iget() reference that we just set in this loop
- * walk. Therefore the following call to iput() will
- * not sleep nor drop the inode because there is now at
- * least two references to it.
- */
- iput(inode);
} else {
spin_unlock(&object->lock);
rcu_read_unlock();
@@ -1479,12 +1468,7 @@ static void hook_sb_delete(struct super_
* disappear from under us until the next loop walk.
*/
spin_unlock(&sb->s_inode_list_lock);
- /*
- * We can now actually put the inode reference from the
- * previous loop walk, which is not needed anymore.
- */
iput(prev_inode);
- cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
prev_inode = inode;
--
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
2025-09-24 0:28 ` Hillf Danton
@ 2025-09-24 9:44 ` Edward Adam Davis
2025-09-24 10:43 ` syzbot
2025-09-24 10:38 ` Edward Adam Davis
` (4 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Edward Adam Davis @ 2025-09-24 9:44 UTC (permalink / raw)
To: syzbot+12479ae15958fc3f54ec; +Cc: linux-kernel, syzkaller-bugs
#syz test
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 4ed997f4a663..a18d53507210 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -1484,7 +1484,6 @@ static void hook_sb_delete(struct super_block *const sb)
* previous loop walk, which is not needed anymore.
*/
iput(prev_inode);
- cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
prev_inode = inode;
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-24 9:44 ` Edward Adam Davis
@ 2025-09-24 10:43 ` syzbot
0 siblings, 0 replies; 14+ messages in thread
From: syzbot @ 2025-09-24 10:43 UTC (permalink / raw)
To: eadavis, linux-kernel, syzkaller-bugs
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: sleeping function called from invalid context in hook_sb_delete
BUG: sleeping function called from invalid context at fs/inode.c:1928
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6514, name: syz.0.17
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
2 locks held by syz.0.17/6514:
#0: ffff8880306a20e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff8880306a20e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff8880306a20e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:505
#1: ffff8880306a2998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#1: ffff8880306a2998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: hook_sb_delete+0xae/0xbc0 security/landlock/fs.c:1405
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 UID: 0 PID: 6514 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
__might_resched+0x495/0x610 kernel/sched/core.c:8960
iput+0x2b/0xc50 fs/inode.c:1928
hook_sb_delete+0x6b7/0xbc0 security/landlock/fs.c:1468
security_sb_delete+0x80/0x150 security/security.c:1467
generic_shutdown_super+0xaa/0x2c0 fs/super.c:634
kill_anon_super fs/super.c:1281 [inline]
kill_litter_super+0x76/0xb0 fs/super.c:1291
deactivate_locked_super+0xbc/0x130 fs/super.c:473
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe6d878eec9
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:00007fe6d961c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fe6d89e5fa0 RCX: 00007fe6d878eec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000002c0
RBP: 00007fe6d8811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe6d89e6038 R14: 00007fe6d89e5fa0 R15: 00007ffc5011e858
</TASK>
Tested on:
commit: ce7f1a98 Add linux-next specific files for 20250923
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=128f94e2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=14e2cce2580000
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
2025-09-24 0:28 ` Hillf Danton
2025-09-24 9:44 ` Edward Adam Davis
@ 2025-09-24 10:38 ` Edward Adam Davis
2025-09-24 10:46 ` Edward Adam Davis
2025-09-24 11:19 ` syzbot
2025-09-24 11:05 ` Jan Kara
` (3 subsequent siblings)
6 siblings, 2 replies; 14+ messages in thread
From: Edward Adam Davis @ 2025-09-24 10:38 UTC (permalink / raw)
To: syzbot+12479ae15958fc3f54ec; +Cc: linux-kernel, syzkaller-bugs
#syz test
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 4ed997f4a663..a18d53507210 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -1484,7 +1484,6 @@ static void hook_sb_delete(struct super_block *const sb)
* previous loop walk, which is not needed anymore.
*/
iput(prev_inode);
- cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
prev_inode = inode;
diff --git a/kernel/fork.c b/kernel/fork.c
index e9a7fb5c3e49..a0b8eeeb1d27 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2349,7 +2349,7 @@ __latent_entropy struct task_struct *copy_process(
if (need_futex_hash_allocate_default(clone_flags)) {
retval = futex_hash_allocate_default();
if (retval)
- goto bad_fork_core_free;
+ goto bad_fork_cancel_cgroup;
/*
* If we fail beyond this point we don't free the allocated
* futex hash map. We assume that another thread will be created
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-24 10:38 ` Edward Adam Davis
@ 2025-09-24 10:46 ` Edward Adam Davis
2025-09-24 10:46 ` syzbot
2025-09-24 11:19 ` syzbot
1 sibling, 1 reply; 14+ messages in thread
From: Edward Adam Davis @ 2025-09-24 10:46 UTC (permalink / raw)
To: eadavis; +Cc: syzbot+12479ae15958fc3f54ec, linux-kernel, syzkaller-bugs
#syz test: none
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-24 10:38 ` Edward Adam Davis
2025-09-24 10:46 ` Edward Adam Davis
@ 2025-09-24 11:19 ` syzbot
1 sibling, 0 replies; 14+ messages in thread
From: syzbot @ 2025-09-24 11:19 UTC (permalink / raw)
To: eadavis, linux-kernel, syzkaller-bugs
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: sleeping function called from invalid context in hook_sb_delete
BUG: sleeping function called from invalid context at fs/inode.c:1928
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6483, name: syz.0.17
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
2 locks held by syz.0.17/6483:
#0: ffff888028f400e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff888028f400e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff888028f400e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:505
#1: ffff888028f40998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#1: ffff888028f40998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: hook_sb_delete+0xae/0xbc0 security/landlock/fs.c:1405
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 0 UID: 0 PID: 6483 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
__might_resched+0x495/0x610 kernel/sched/core.c:8960
iput+0x2b/0xc50 fs/inode.c:1928
hook_sb_delete+0x6b7/0xbc0 security/landlock/fs.c:1468
security_sb_delete+0x80/0x150 security/security.c:1467
generic_shutdown_super+0xaa/0x2c0 fs/super.c:634
kill_anon_super fs/super.c:1281 [inline]
kill_litter_super+0x76/0xb0 fs/super.c:1291
deactivate_locked_super+0xbc/0x130 fs/super.c:473
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8b7e78eec9
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:00007f8b7f714038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f8b7e9e5fa0 RCX: 00007f8b7e78eec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000002c0
RBP: 00007f8b7e811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8b7e9e6038 R14: 00007f8b7e9e5fa0 R15: 00007ffe75b4a848
</TASK>
Tested on:
commit: ce7f1a98 Add linux-next specific files for 20250923
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13644f12580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=11724d34580000
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
` (2 preceding siblings ...)
2025-09-24 10:38 ` Edward Adam Davis
@ 2025-09-24 11:05 ` Jan Kara
2025-09-29 8:51 ` Christian Brauner
2025-10-09 20:56 ` syzbot
` (2 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Jan Kara @ 2025-09-24 11:05 UTC (permalink / raw)
To: syzbot
Cc: brauner, jack, linux-fsdevel, linux-kernel, syzkaller-bugs, viro,
Mickaël Salaün, linux-security-module,
Günther Noack
Hello!
Added Landlock guys to CC since this is a bug in Landlock.
On Tue 23-09-25 15:59:37, syzbot wrote:
> syzbot found the following issue on:
>
> HEAD commit: ce7f1a983b07 Add linux-next specific files for 20250923
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=118724e2580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
> dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
> 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=1376e27c580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136e78e2580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/c30be6f36c31/disk-ce7f1a98.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/ae9ea347d4d8/vmlinux-ce7f1a98.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/d59682a4f33c/bzImage-ce7f1a98.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+12479ae15958fc3f54ec@syzkaller.appspotmail.com
>
> BUG: sleeping function called from invalid context at fs/inode.c:1928
The first catch from the new might_sleep() annotations in iput().
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6028, name: syz.0.17
> preempt_count: 1, expected: 0
> RCU nest depth: 0, expected: 0
> 2 locks held by syz.0.17/6028:
> #0: ffff8880326bc0e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
> #0: ffff8880326bc0e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
> #0: ffff8880326bc0e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:505
> #1: ffff8880326bc998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
> #1: ffff8880326bc998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: hook_sb_delete+0xae/0xbd0 security/landlock/fs.c:1405
> Preemption disabled at:
> [<0000000000000000>] 0x0
> CPU: 0 UID: 0 PID: 6028 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
> Call Trace:
> <TASK>
> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
> __might_resched+0x495/0x610 kernel/sched/core.c:8960
> iput+0x2b/0xc50 fs/inode.c:1928
> hook_sb_delete+0x6b5/0xbd0 security/landlock/fs.c:1468
Indeed looks like a bug because we can call iput() while holding
sb->s_inode_list_lock in one case in hook_sb_delete().
Honza
> security_sb_delete+0x80/0x150 security/security.c:1467
> generic_shutdown_super+0xaa/0x2c0 fs/super.c:634
> kill_anon_super fs/super.c:1281 [inline]
> kill_litter_super+0x76/0xb0 fs/super.c:1291
> deactivate_locked_super+0xbc/0x130 fs/super.c:473
> cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327
> task_work_run+0x1d4/0x260 kernel/task_work.c:227
> resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
> exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
> exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
> syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
> syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
> do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fc08e18eec9
> 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:00007ffcd5efff18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
> RAX: 0000000000000000 RBX: 00007fc08e3e5fa0 RCX: 00007fc08e18eec9
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000002c0
> RBP: 00007fc08e211f91 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fc08e3e5fa0 R14: 00007fc08e3e5fa0 R15: 0000000000000002
> </TASK>
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> 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.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-24 11:05 ` Jan Kara
@ 2025-09-29 8:51 ` Christian Brauner
0 siblings, 0 replies; 14+ messages in thread
From: Christian Brauner @ 2025-09-29 8:51 UTC (permalink / raw)
To: Jan Kara
Cc: syzbot, linux-fsdevel, linux-kernel, syzkaller-bugs, viro,
Mickaël Salaün, linux-security-module,
Günther Noack
On Wed, Sep 24, 2025 at 01:05:03PM +0200, Jan Kara wrote:
> Hello!
>
> Added Landlock guys to CC since this is a bug in Landlock.
>
> On Tue 23-09-25 15:59:37, syzbot wrote:
> > syzbot found the following issue on:
> >
> > HEAD commit: ce7f1a983b07 Add linux-next specific files for 20250923
> > git tree: linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=118724e2580000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
> > 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=1376e27c580000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136e78e2580000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/c30be6f36c31/disk-ce7f1a98.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/ae9ea347d4d8/vmlinux-ce7f1a98.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/d59682a4f33c/bzImage-ce7f1a98.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+12479ae15958fc3f54ec@syzkaller.appspotmail.com
> >
> > BUG: sleeping function called from invalid context at fs/inode.c:1928
>
> The first catch from the new might_sleep() annotations in iput().
>
> > in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6028, name: syz.0.17
> > preempt_count: 1, expected: 0
> > RCU nest depth: 0, expected: 0
> > 2 locks held by syz.0.17/6028:
> > #0: ffff8880326bc0e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
> > #0: ffff8880326bc0e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
> > #0: ffff8880326bc0e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:505
> > #1: ffff8880326bc998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
> > #1: ffff8880326bc998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: hook_sb_delete+0xae/0xbd0 security/landlock/fs.c:1405
> > Preemption disabled at:
> > [<0000000000000000>] 0x0
> > CPU: 0 UID: 0 PID: 6028 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
> > Call Trace:
> > <TASK>
> > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
> > __might_resched+0x495/0x610 kernel/sched/core.c:8960
> > iput+0x2b/0xc50 fs/inode.c:1928
> > hook_sb_delete+0x6b5/0xbd0 security/landlock/fs.c:1468
>
> Indeed looks like a bug because we can call iput() while holding
> sb->s_inode_list_lock in one case in hook_sb_delete().
Very nice that the annotations help finding this!
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
` (3 preceding siblings ...)
2025-09-24 11:05 ` Jan Kara
@ 2025-10-09 20:56 ` syzbot
2025-11-01 15:32 ` Forwarded: " syzbot
2025-11-05 19:38 ` Forwarded: [PATCH v1] fs: Move might_sleep() annotation to iput_final() syzbot
6 siblings, 0 replies; 14+ messages in thread
From: syzbot @ 2025-10-09 20:56 UTC (permalink / raw)
To: brauner, eadavis, gnoack, hdanton, jack, linux-fsdevel,
linux-kernel, linux-security-module, max.kellermann, mic,
syzkaller-bugs, twuufnxlz, viro
syzbot has bisected this issue to:
commit 2ef435a872abc347dc0a92f1c213bb0af3cbf195
Author: Max Kellermann <max.kellermann@ionos.com>
Date: Wed Sep 17 15:36:31 2025 +0000
fs: add might_sleep() annotation to iput() and more
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1092ba7c580000
start commit: 7c3ba4249a36 Add linux-next specific files for 20251008
git tree: linux-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=1292ba7c580000
console output: https://syzkaller.appspot.com/x/log.txt?x=1492ba7c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fa7a95b14b1eaa
dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12280dcd980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111d852f980000
Reported-by: syzbot+12479ae15958fc3f54ec@syzkaller.appspotmail.com
Fixes: 2ef435a872ab ("fs: add might_sleep() annotation to iput() and more")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
^ permalink raw reply [flat|nested] 14+ messages in thread* Forwarded: Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
` (4 preceding siblings ...)
2025-10-09 20:56 ` syzbot
@ 2025-11-01 15:32 ` syzbot
2025-11-05 19:38 ` Forwarded: [PATCH v1] fs: Move might_sleep() annotation to iput_final() syzbot
6 siblings, 0 replies; 14+ messages in thread
From: syzbot @ 2025-11-01 15:32 UTC (permalink / raw)
To: linux-kernel
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.
***
Subject: Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete
Author: m@maowtm.org
#syz test
diff --git a/fs/inode.c b/fs/inode.c
index 1396f79b2551..b28a61978d88 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -812,6 +812,8 @@ static void evict(struct inode *inode)
{
const struct super_operations *op = inode->i_sb->s_op;
+ might_sleep();
+
BUG_ON(!(inode_state_read_once(inode) & I_FREEING));
BUG_ON(!list_empty(&inode->i_lru));
@@ -1968,7 +1970,6 @@ static void iput_final(struct inode *inode)
*/
void iput(struct inode *inode)
{
- might_sleep();
if (unlikely(!inode))
return;
^ permalink raw reply related [flat|nested] 14+ messages in thread* Forwarded: [PATCH v1] fs: Move might_sleep() annotation to iput_final()
2025-09-23 22:59 [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb_delete syzbot
` (5 preceding siblings ...)
2025-11-01 15:32 ` Forwarded: " syzbot
@ 2025-11-05 19:38 ` syzbot
6 siblings, 0 replies; 14+ messages in thread
From: syzbot @ 2025-11-05 19:38 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: [PATCH v1] fs: Move might_sleep() annotation to iput_final()
Author: mic@digikod.net
iput() don't directly call any sleepable code but mostly checks flags
and decrement a reference counter before calling iput_final() and then
evict().
Some code might call iput() with guarantees that iput_final() will not
be called. This is the case for Landlock's hook_sb_delete() where the
inode counter must de decremented while holding it with another
reference, see comment above the first iput() call.
Move the new might_sleep() call from iput() to iput_final(). The
alternative would be to manually decrement the counter without calling
iput(), but it doesn't seem right.
Cc: Christian Brauner <brauner@kernel.org>
Cc: Edward Adam Davis <eadavis@qq.com>
Cc: Günther Noack <gnoack@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Tingmao Wang <m@maowtm.org>
Reported-by: syzbot+12479ae15958fc3f54ec@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68d32659.a70a0220.4f78.0012.GAE@google.com/
Fixes: 2ef435a872ab ("fs: add might_sleep() annotation to iput() and more")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
From hook_sb_delete():
/*
* At this point, we own the ihold() reference that was
* originally set up by get_inode_object() and the
* __iget() reference that we just set in this loop
* walk. Therefore the following call to iput() will
* not sleep nor drop the inode because there is now at
* least two references to it.
*/
iput(inode);
#syz test
---
fs/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/inode.c b/fs/inode.c
index 84f539497857..64120cb21e8b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1917,6 +1917,7 @@ static void iput_final(struct inode *inode)
const struct super_operations *op = inode->i_sb->s_op;
int drop;
+ might_sleep();
WARN_ON(inode_state_read(inode) & I_NEW);
VFS_BUG_ON_INODE(atomic_read(&inode->i_count) != 0, inode);
@@ -1969,7 +1970,6 @@ static void iput_final(struct inode *inode)
*/
void iput(struct inode *inode)
{
- might_sleep();
if (unlikely(!inode))
return;
--
2.51.0
^ permalink raw reply related [flat|nested] 14+ messages in thread