Date:   Sun, 31 Jan 2021 09:42:53 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, andrii@...nel.org,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>, kpsingh@...nel.org,
        netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: corrupted pvqspinlock in htab_map_update_elem

Hi,

I am testing the following the program:
https://gist.github.com/dvyukov/e5c0a8ef220ef856363c1080b0936a9e
on the latest upstream 6642d600b541b81931fb1ab0c041b0d68f77be7e and
getting the following crash. Config is:
https://gist.github.com/dvyukov/16d9905e5ef35e44285451f1d330ddbc

The program updates a bpf map from a program called on hw breakpoint
hit. Not sure if it's a bpf issue or a perf issue. This time it is not
a fuzzer workload, I am trying to do something useful :)

------------[ cut here ]------------
pvqspinlock: lock 0xffffffff8f371d80 has corrupted value 0x0!
WARNING: CPU: 3 PID: 8771 at kernel/locking/qspinlock_paravirt.h:498
__pv_queued_spin_unlock_slowpath+0x22e/0x2b0
kernel/locking/qspinlock_paravirt.h:498
Modules linked in:
CPU: 3 PID: 8771 Comm: a.out Not tainted 5.11.0-rc5+ #71
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.13.0-44-g88ab0c15525c-prebuilt.qemu.org 04/01/2014
RIP: 0010:__pv_queued_spin_unlock_slowpath+0x22e/0x2b0
kernel/locking/qspinlock_paravirt.h:498
Code: ea 03 0f b6 14 02 4c 89 e8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2
75 62 41 8b 55 00 4c 89 ee 48 c7 c7 20 6b 4c 89 e8 72 d3 5f 07 <0f> 0b
e9 6cc
RSP: 0018:fffffe00000c17b0 EFLAGS: 00010086
RAX: 0000000000000000 RBX: ffffffff8f3b5660 RCX: 0000000000000000
RDX: ffff8880150222c0 RSI: ffffffff815b624d RDI: fffffbc0000182e8
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff817de94f R11: 0000000000000000 R12: ffff8880150222c0
R13: ffffffff8f371d80 R14: ffff8880181fead8 R15: 0000000000000000
FS:  00007fa5b51f0700(0000) GS:ffff88802cf80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000002286908 CR3: 0000000015b24000 CR4: 0000000000750ee0
DR0: 00000000004cb3d4 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <#DB>
 __raw_callee_save___pv_queued_spin_unlock_slowpath+0x11/0x20
 .slowpath+0x9/0xe
 pv_queued_spin_unlock arch/x86/include/asm/paravirt.h:559 [inline]
 queued_spin_unlock arch/x86/include/asm/qspinlock.h:56 [inline]
 lockdep_unlock+0x10e/0x290 kernel/locking/lockdep.c:124
 debug_locks_off_graph_unlock kernel/locking/lockdep.c:165 [inline]
 print_usage_bug kernel/locking/lockdep.c:3710 [inline]
 verify_lock_unused kernel/locking/lockdep.c:5374 [inline]
 lock_acquire kernel/locking/lockdep.c:5433 [inline]
 lock_acquire+0x471/0x720 kernel/locking/lockdep.c:5407
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
 htab_lock_bucket kernel/bpf/hashtab.c:175 [inline]
 htab_map_update_elem+0x1f0/0x790 kernel/bpf/hashtab.c:1023
 bpf_prog_60236c52b8017ad1+0x8e/0xab4
 bpf_dispatcher_nop_func include/linux/bpf.h:651 [inline]
 bpf_overflow_handler+0x192/0x5b0 kernel/events/core.c:9755
 __perf_event_overflow+0x13c/0x370 kernel/events/core.c:8979
 perf_swevent_overflow kernel/events/core.c:9055 [inline]
 perf_swevent_event+0x347/0x550 kernel/events/core.c:9083
 perf_bp_event+0x1a2/0x1c0 kernel/events/core.c:9932
 hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:535 [inline]
 hw_breakpoint_exceptions_notify+0x18a/0x3b0 arch/x86/kernel/hw_breakpoint.c:567
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 atomic_notifier_call_chain+0x8d/0x170 kernel/notifier.c:217
 notify_die+0xda/0x170 kernel/notifier.c:548
 notify_debug+0x20/0x30 arch/x86/kernel/traps.c:842
 exc_debug_kernel arch/x86/kernel/traps.c:902 [inline]
 exc_debug+0x103/0x140 arch/x86/kernel/traps.c:998
 asm_exc_debug+0x19/0x30 arch/x86/include/asm/idtentry.h:598
RIP: 0010:copy_user_generic_unrolled+0xa2/0xc0 arch/x86/lib/copy_user_64.S:102
Code: ff c9 75 b6 89 d1 83 e2 07 c1 e9 03 74 12 4c 8b 06 4c 89 07 48
8d 76 08 48 8d 7f 08 ff c9 75 ee 21 d2 74 10 89 d1 8a 06 88 07 <48> ff
c6 484
RSP: 0018:ffffc90000d67af0 EFLAGS: 00040202
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffff88801341d001 RDI: 00000000004cb3d4
RBP: 00000000004cb3d4 R08: 0000000000000000 R09: ffff88801341d001
R10: ffffed1002683a00 R11: 0000000000000000 R12: ffff88801341d001
R13: 00000000004cb3d5 R14: 0000000000000000 R15: 0000000000000001
 </#DB>
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
 copyout.part.0+0xe4/0x110 lib/iov_iter.c:148
 copyout lib/iov_iter.c:182 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:219 [inline]
 copy_page_to_iter+0x416/0xed0 lib/iov_iter.c:926
 pipe_read+0x4a4/0x13a0 fs/pipe.c:290
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read+0x5b7/0x6e0 fs/read_write.c:415
 vfs_read+0x35c/0x570 fs/read_write.c:496
 ksys_read+0x1ee/0x250 fs/read_write.c:634
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x406c1c
Code: ec 28 48 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 fc ff ff
48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 31 c0 0f 05 <48> 3d
00 f08
RSP: 002b:00007fa5b51f02d0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000004cb3d4 RCX: 0000000000406c1c
RDX: 0000000000000001 RSI: 00000000004cb3d4 RDI: 0000000000000004
RBP: 00007fa5b51f030c R08: 0000000000000000 R09: 0000000000000000
R10: 00007fa5b51f0700 R11: 0000000000000246 R12: 00000000004cb3d0
R13: cccccccccccccccd R14: 00007fa5b51f0400 R15: 0000000000802000

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