Re: [syzbot] BUG: spinlock bad magic in synchronize_srcu

From: syzbot
Date: Sun Sep 12 2021 - 16:45:24 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: 78e709522d2c Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16131d2b300000
kernel config: https://syzkaller.appspot.com/x/.config?x=2150ebd7e72fa695
dashboard link: https://syzkaller.appspot.com/bug?extid=05017ad275a64a3246f8
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10b72895300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14c42853300000

The issue was bisected to:

commit 5c313e22d61f8c27ab001ec40f823d2a19cd5e68
Author: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Date: Thu Oct 8 05:26:39 2020 +0000

Merge remote-tracking branch 'usb/usb-next' into master

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15864a10500000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17864a10500000
console output: https://syzkaller.appspot.com/x/log.txt?x=13864a10500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+05017ad275a64a3246f8@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 5c313e22d61f ("Merge remote-tracking branch 'usb/usb-next' into master")

BUG: spinlock bad magic on CPU#0, syz-executor959/7639
lock: 0xffff8880b9c00040, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
CPU: 0 PID: 7639 Comm: syz-executor959 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
debug_spin_lock_before kernel/locking/spinlock_debug.c:85 [inline]
do_raw_spin_lock+0x216/0x2b0 kernel/locking/spinlock_debug.c:114
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline]
_raw_spin_lock_irqsave+0x41/0x50 kernel/locking/spinlock.c:162
srcu_might_be_idle kernel/rcu/srcutree.c:767 [inline]
synchronize_srcu+0x4f/0x1c0 kernel/rcu/srcutree.c:1008
kvm_mmu_uninit_vm+0x18/0x30 arch/x86/kvm/mmu/mmu.c:5711
kvm_arch_destroy_vm+0x4e7/0x680 arch/x86/kvm/x86.c:11331
kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1094 [inline]
kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:4583 [inline]
kvm_dev_ioctl+0x12e3/0x1ac0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4638
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4458f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb1165fa278 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004ca410 RCX: 00000000004458f9
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000003
RBP: 00000000004ca41c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000049a0ac
R13: 00007fb1165fa280 R14: 6d766b2f7665642f R15: 00000000004ca418
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 7639 Comm: syz-executor959 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:rcu_segcblist_enqueue+0xb9/0x130 kernel/rcu/rcu_segcblist.c:348
Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 4e 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 20 48 89 ea 48 c1 ea 03 <80> 3c 02 00 75 21 48 89 75 00 48 89 73 20 48 83 c4 08 5b 5d c3 48
RSP: 0018:ffffc90003287be0 EFLAGS: 00010046
RAX: dffffc0000000000 RBX: ffff8880b9d00080 RCX: ffffffff815bd1d0
RDX: 0000000000000000 RSI: ffffc90003287cc8 RDI: ffff8880b9d000a0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003
R10: fffff52000650f6e R11: 0000000000000000 R12: ffffc90003287cc8
R13: ffff8880b9d00080 R14: 0000000000000000 R15: ffff8880b9d00040
FS: 00007fb1165fa700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1165d9718 CR3: 000000006ab6b000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
srcu_gp_start_if_needed+0x116/0xbc0 kernel/rcu/srcutree.c:823
__call_srcu kernel/rcu/srcutree.c:883 [inline]
__synchronize_srcu+0x21f/0x290 kernel/rcu/srcutree.c:929
kvm_mmu_uninit_vm+0x18/0x30 arch/x86/kvm/mmu/mmu.c:5711
kvm_arch_destroy_vm+0x4e7/0x680 arch/x86/kvm/x86.c:11331
kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1094 [inline]
kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:4583 [inline]
kvm_dev_ioctl+0x12e3/0x1ac0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4638
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4458f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb1165fa278 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004ca410 RCX: 00000000004458f9
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000003
RBP: 00000000004ca41c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000049a0ac
R13: 00007fb1165fa280 R14: 6d766b2f7665642f R15: 00000000004ca418
Modules linked in:
---[ end trace 3a47816aa768583b ]---
RIP: 0010:rcu_segcblist_enqueue+0xb9/0x130 kernel/rcu/rcu_segcblist.c:348
Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 4e 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 20 48 89 ea 48 c1 ea 03 <80> 3c 02 00 75 21 48 89 75 00 48 89 73 20 48 83 c4 08 5b 5d c3 48
RSP: 0018:ffffc90003287be0 EFLAGS: 00010046
RAX: dffffc0000000000 RBX: ffff8880b9d00080 RCX: ffffffff815bd1d0
RDX: 0000000000000000 RSI: ffffc90003287cc8 RDI: ffff8880b9d000a0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003
R10: fffff52000650f6e R11: 0000000000000000 R12: ffffc90003287cc8
R13: ffff8880b9d00080 R14: 0000000000000000 R15: ffff8880b9d00040
FS: 00007fb1165fa700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1165d9718 CR3: 000000006ab6b000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 7 bytes skipped:
0: df 48 89 fisttps -0x77(%rax)
3: fa cli
4: 48 c1 ea 03 shr $0x3,%rdx
8: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
c: 75 4e jne 0x5c
e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
15: fc ff df
18: 48 8b 6b 20 mov 0x20(%rbx),%rbp
1c: 48 89 ea mov %rbp,%rdx
1f: 48 c1 ea 03 shr $0x3,%rdx
* 23: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
27: 75 21 jne 0x4a
29: 48 89 75 00 mov %rsi,0x0(%rbp)
2d: 48 89 73 20 mov %rsi,0x20(%rbx)
31: 48 83 c4 08 add $0x8,%rsp
35: 5b pop %rbx
36: 5d pop %rbp
37: c3 retq
38: 48 rex.W