[syzbot] [bpf?] possible deadlock in stack_depot_save_flags

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 977b1ef51866 Merge tag 'block-6.9-20240420' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e9daf5180000
kernel config: https://syzkaller.appspot.com/x/.config?x=d239903bd07761e5
dashboard link: https://syzkaller.appspot.com/bug?extid=c065d8dfbb5ad8cbdceb
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/08d7b6e107aa/disk-977b1ef5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9c5e543ffdcf/vmlinux-977b1ef5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/04a6d79d2f69/bzImage-977b1ef5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c065d8...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc4-syzkaller-00266-g977b1ef51866 #0 Not tainted
------------------------------------------------------
syz-executor.3/5489 is trying to acquire lock:
ffffffff8ea48ea8 (pool_lock#2){-.-.}-{2:2}, at: stack_depot_save_flags+0x240/0x830 lib/stackdepot.c:640

but task is already holding lock:
ffff8880121cf9f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xcb/0xc10 kernel/bpf/lpm_trie.c:324

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&trie->lock){-.-.}-{2:2}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
trie_delete_elem+0x96/0x6a0 kernel/bpf/lpm_trie.c:451
0xffffffffa0000856
bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
__bpf_prog_run include/linux/filter.h:657 [inline]
bpf_prog_run include/linux/filter.h:664 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
bpf_trace_run2+0x206/0x420 kernel/trace/bpf_trace.c:2420
trace_contention_end+0x114/0x140 include/trace/events/lock.h:122
__pv_queued_spin_lock_slowpath+0x939/0xc60 kernel/locking/qspinlock.c:560
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock+0x272/0x370 kernel/locking/spinlock_debug.c:116
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
_raw_spin_lock_irqsave+0xe1/0x120 kernel/locking/spinlock.c:162
stack_depot_save_flags+0x240/0x830 lib/stackdepot.c:640
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_save_track+0x51/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kfree+0x153/0x3a0 mm/slub.c:4390
find_tree_dqentry+0xc3c/0xfb0 fs/quota/quota_tree.c:702
find_tree_dqentry+0x6cd/0xfb0 fs/quota/quota_tree.c:698
find_dqentry fs/quota/quota_tree.c:716 [inline]
qtree_read_dquot+0x53e/0x7e0 fs/quota/quota_tree.c:736
v2_read_dquot+0x11e/0x200 fs/quota/quota_v2.c:344
dquot_acquire+0x194/0x680 fs/quota/dquot.c:463
ext4_acquire_dquot+0x301/0x4c0 fs/ext4/super.c:6882
dqget+0x772/0xeb0 fs/quota/dquot.c:977
__dquot_initialize+0x468/0xec0 fs/quota/dquot.c:1505
ext4_create+0xb5/0x550 fs/ext4/namei.c:2823
lookup_open fs/namei.c:3497 [inline]
open_last_lookups fs/namei.c:3566 [inline]
path_openat+0x1427/0x3240 fs/namei.c:3796
do_filp_open+0x235/0x490 fs/namei.c:3826
do_sys_openat2+0x13e/0x1d0 fs/open.c:1406
do_sys_open fs/open.c:1421 [inline]
__do_sys_creat fs/open.c:1497 [inline]
__se_sys_creat fs/open.c:1491 [inline]
__x64_sys_creat+0x123/0x170 fs/open.c:1491
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

-> #0 (pool_lock#2){-.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
__lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
stack_depot_save_flags+0x240/0x830 lib/stackdepot.c:640
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_save_track+0x51/0x80 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+0x253/0x4e0 mm/slub.c:3973
kmalloc_node include/linux/slab.h:648 [inline]
bpf_map_kmalloc_node+0xd3/0x1c0 kernel/bpf/syscall.c:422
lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
trie_update_elem+0x1d3/0xc10 kernel/bpf/lpm_trie.c:333
bpf_map_update_value+0x4d5/0x540 kernel/bpf/syscall.c:203
map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
__sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5648
__do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
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

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&trie->lock);
lock(pool_lock#2);
lock(&trie->lock);
lock(pool_lock#2);

*** DEADLOCK ***

2 locks held by syz-executor.3/5489:
#0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
#0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
#0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x3c4/0x540 kernel/bpf/syscall.c:202
#1: ffff8880121cf9f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xcb/0xc10 kernel/bpf/lpm_trie.c:324

stack backtrace:
CPU: 1 PID: 5489 Comm: syz-executor.3 Not tainted 6.9.0-rc4-syzkaller-00266-g977b1ef51866 #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
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
__lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
stack_depot_save_flags+0x240/0x830 lib/stackdepot.c:640
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_save_track+0x51/0x80 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+0x253/0x4e0 mm/slub.c:3973
kmalloc_node include/linux/slab.h:648 [inline]
bpf_map_kmalloc_node+0xd3/0x1c0 kernel/bpf/syscall.c:422
lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
trie_update_elem+0x1d3/0xc10 kernel/bpf/lpm_trie.c:333
bpf_map_update_value+0x4d5/0x540 kernel/bpf/syscall.c:203
map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
__sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5648
__do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
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: 0033:0x7efe77c7dea9
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:00007efe789050c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007efe77dabf80 RCX: 00007efe77c7dea9
RDX: 0000000000000020 RSI: 00000000200002c0 RDI: 0000000000000002
RBP: 00007efe77cca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007efe77dabf80 R15: 00007fffff8122a8
</TASK>


---
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