Message-ID: <6746c52d.050a0220.1286eb.002b.GAE@google.com>
Date: Tue, 26 Nov 2024 23:07:25 -0800
From: syzbot <syzbot+c6c4861455fdd207f160@...kaller.appspotmail.com>
To: andrii@...nel.org, asml.silence@...il.com, ast@...nel.org, axboe@...nel.dk, 
	bpf@...r.kernel.org, daniel@...earbox.net, eddyz87@...il.com, 
	haoluo@...gle.com, john.fastabend@...il.com, jolsa@...nel.org, 
	kpsingh@...nel.org, linux-kernel@...r.kernel.org, martin.lau@...ux.dev, 
	mingo@...nel.org, netdev@...r.kernel.org, peterz@...radead.org, 
	riel@...hat.com, sdf@...ichev.me, sdf@...gle.com, song@...nel.org, 
	syzkaller-bugs@...glegroups.com, wander@...hat.com, yhs@...com, 
	yonghong.song@...ux.dev
Subject: Re: [syzbot] [bpf?] BUG: MAX_STACK_TRACE_ENTRIES too low! (4)

syzbot has found a reproducer for the following issue on:

HEAD commit:    445d9f05fa14 Merge tag 'nfsd-6.13' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1693d530580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3c44a32edb32752c
dashboard link: https://syzkaller.appspot.com/bug?extid=c6c4861455fdd207f160
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15abb778580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11977ff7980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-445d9f05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a928f58090e0/vmlinux-445d9f05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4212b152a056/bzImage-445d9f05.xz

The issue was bisected to:

commit 893cdaaa3977be6afb3a7f756fbfd7be83f68d8c
Author: Wander Lairson Costa <wander@...hat.com>
Date:   Wed Jun 14 12:23:22 2023 +0000

    sched: avoid false lockdep splat in put_task_struct()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14a00127980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=16a00127980000
console output: https://syzkaller.appspot.com/x/log.txt?x=12a00127980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c6c4861455fdd207f160@...kaller.appspotmail.com
Fixes: 893cdaaa3977 ("sched: avoid false lockdep splat in put_task_struct()")

BUG: MAX_STACK_TRACE_ENTRIES too low!
turning off the locking correctness validator.
CPU: 1 UID: 0 PID: 5965 Comm: sshd Not tainted 6.12.0-syzkaller-09734-g445d9f05fa14 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 save_trace+0x78f/0xb60 kernel/locking/lockdep.c:579
 check_prev_add kernel/locking/lockdep.c:3222 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x312a/0x3c40 kernel/locking/lockdep.c:5226
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
 htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
 bpf_prog_2c29ac5cdc6b1842+0x43/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
 bpf_trace_run3+0x240/0x5a0 kernel/trace/bpf_trace.c:2393
 trace_kmem_cache_free include/trace/events/kmem.h:114 [inline]
 kmem_cache_free+0x200/0x4c0 mm/slub.c:4699
 skb_kfree_head net/core/skbuff.c:1084 [inline]
 skb_kfree_head net/core/skbuff.c:1081 [inline]
 skb_free_head+0x18a/0x1d0 net/core/skbuff.c:1098
 skb_release_data+0x560/0x730 net/core/skbuff.c:1125
 skb_release_all net/core/skbuff.c:1190 [inline]
 __kfree_skb+0x4f/0x70 net/core/skbuff.c:1204
 tcp_wmem_free_skb include/net/tcp.h:306 [inline]
 tcp_rtx_queue_unlink_and_free include/net/tcp.h:2091 [inline]
 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3436 [inline]
 tcp_ack+0x1eb7/0x5ba0 net/ipv4/tcp_input.c:4032
 tcp_rcv_established+0xcab/0x20f0 net/ipv4/tcp_input.c:6173
 tcp_v4_do_rcv+0x5ca/0xa90 net/ipv4/tcp_ipv4.c:1916
 sk_backlog_rcv include/net/sock.h:1121 [inline]
 __release_sock+0x31b/0x400 net/core/sock.c:3083
 release_sock+0x5a/0x220 net/core/sock.c:3637
 tcp_sendmsg+0x38/0x50 net/ipv4/tcp.c:1359
 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg net/socket.c:726 [inline]
 sock_write_iter+0x4ac/0x5b0 net/socket.c:1147
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0x5ae/0x1150 fs/read_write.c:679
 ksys_write+0x207/0x250 fs/read_write.c:731
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f850c116bf2
Code: 89 c7 48 89 44 24 08 e8 7b 34 fa ff 48 8b 44 24 08 48 83 c4 28 c3 c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 6f 48 8b 15 07 a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fffe9a02c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007f850c116bf2
RDX: 0000000000000034 RSI: 0000559808160970 RDI: 0000000000000004
RBP: 0000559808169290 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00005597d5bb7aa4
R13: 00000000000000f4 R14: 00005597d5bb83e8 R15: 00007fffe9a02ce8
 </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.

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