[syzbot] [bpf?] possible deadlock in trie_delete_elem

syzbot
2024-03-20T08:42:21Z

Hello,

syzbot found the following issue on:

HEAD commit: 32fa4366cc4d net: phy: fix phy_read_poll_timeout argument ..
git tree: net
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16f5d769180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=9d95beb2a3c260622518
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=14572985180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1676fc6e180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bb05871df8fc/disk-32fa4366.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a774323fb6ec/vmlinux-32fa4366.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1742ae20d76c/bzImage-32fa4366.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d95beb2a3c260622518@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected
6.8.0-syzkaller-05242-g32fa4366cc4d #0 Not tainted
--------------------------------------------
syz-executor217/5072 is trying to acquire lock:
ffff88802a0fd9f8 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x96/0x6a0 kernel/bpf/lpm_trie.c:451

but task is already holding lock:
ffff88802a0fc9f8 (&trie->lock){....}-{2:2}, at: trie_update_elem+0xcb/0xc10 kernel/bpf/lpm_trie.c:324

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&trie->lock);
lock(&trie->lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by syz-executor217/5072:
#0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x3c4/0x540 kernel/bpf/syscall.c:202
#1: ffff88802a0fc9f8 (&trie->lock){....}-{2:2}, at: trie_update_elem+0xcb/0xc10 kernel/bpf/lpm_trie.c:324
#2: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#2: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#2: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline]
#2: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run4+0x16e/0x490 kernel/trace/bpf_trace.c:2422

stack backtrace:
CPU: 0 PID: 5072 Comm: syz-executor217 Not tainted 6.8.0-syzkaller-05242-g32fa4366cc4d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
check_deadlock kernel/locking/lockdep.c:3062 [inline]
validate_chain+0x15c1/0x58e0 kernel/locking/lockdep.c:3856
__lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1e4/0x530 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
bpf_prog_2c29ac5cdc6b1842+0x42/0x46
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_run4+0x25a/0x490 kernel/trace/bpf_trace.c:2422
trace_mm_page_alloc include/trace/events/kmem.h:177 [inline]
__alloc_pages+0x657/0x680 mm/page_alloc.c:4591
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
__kmalloc_large_node+0x91/0x1f0 mm/slub.c:3926
__do_kmalloc_node mm/slub.c:3969 [inline]
__kmalloc_node+0x33c/0x4e0 mm/slub.c:3988
kmalloc_node include/linux/slab.h:610 [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+0x4d3/0x540 kernel/bpf/syscall.c:203
map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
__sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5619
__do_sys_bpf kernel/bpf/syscall.c:5738 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5736 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736
do_syscall_64+0xfb/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f933485e7a9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc8852b528 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX:

---
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