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WARNING: suspicious RCU usage in kvm_vcpu_memslots

Status: upstream: reported C repro on 2023/03/10 11:13
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+a703fc5de924fa2e1ae8@syzkaller.appspotmail.com
First crash: 773d, last: 7d13h
Fix bisection: the issue occurs on the latest tested release (bisect log)
Crash: WARNING: suspicious RCU usage in kvm_vcpu_gfn_to_memslot (log)
Repro: C syz .config
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2023/05/05 linux-5.15.y (ToT) 8a7f2a5c5aa1 C [report] WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/05/05 upstream (ToT) 78b421b6a7c6 C Didn't crash
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2025/04/03 13:10 14m retest repro linux-5.15.y report log
2025/03/12 15:20 9m retest repro linux-5.15.y report log
2025/03/12 15:20 9m retest repro linux-5.15.y report log
2025/03/12 15:20 11m retest repro linux-5.15.y report log
2025/03/12 15:20 13m retest repro linux-5.15.y report log
2025/03/12 15:20 10m retest repro linux-5.15.y report log
2025/02/05 18:08 13m retest repro linux-5.15.y report log
2025/02/05 18:08 9m retest repro linux-5.15.y report log
2024/12/30 00:40 16m retest repro linux-5.15.y report log
2024/12/30 00:40 12m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2023/09/15 12:26 1h55m fix candidate upstream OK (0) job log
2023/06/18 19:09 34m bisect fix linux-5.15.y OK (0) job log log
2023/04/29 00:11 34m bisect fix linux-5.15.y OK (0) job log log

Sample crash report:
L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.
=============================
WARNING: suspicious RCU usage
5.15.178-syzkaller #0 Not tainted
-----------------------------
include/linux/kvm_host.h:880 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor411/4162:
 #0: ffff8880795c40c8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x1d4/0xcf0 virt/kvm/kvm_main.c:3871

stack backtrace:
CPU: 1 PID: 4162 Comm: syz-executor411 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 __kvm_memslots include/linux/kvm_host.h:878 [inline]
 kvm_vcpu_memslots+0x1b7/0x200 include/linux/kvm_host.h:892
 kvm_vcpu_gfn_to_memslot+0x2b/0x390 virt/kvm/kvm_main.c:2158
 kvm_vcpu_unmap+0x5d/0x80 virt/kvm/kvm_main.c:2773
 nested_vmx_vmexit+0x1476/0x2b70 arch/x86/kvm/vmx/nested.c:4676
 vmx_leave_nested+0x7d/0xb0 arch/x86/kvm/vmx/nested.c:6342
 kvm_leave_nested arch/x86/kvm/x86.c:618 [inline]
 kvm_vcpu_ioctl_x86_set_vcpu_events+0x8d8/0x10e0 arch/x86/kvm/x86.c:4810
 kvm_arch_vcpu_ioctl+0x120e/0x1d40 arch/x86/kvm/x86.c:5295
 kvm_vcpu_ioctl+0x6db/0xcf0 virt/kvm/kvm_main.c:4050
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fa67ec32639
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:00007ffd7bcbc788 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000400000000000 RCX: 00007fa67ec32639
RDX: 0000400000000280 RSI: 000000004040aea0 RDI: 0000000000000005
RBP: 00007fa67eca5610 R08: 00007ffd7bcbc958 R09: 00007ffd7bcbc958
R10:

Crashes (172):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/12 08:12 linux-5.15.y c16c81c81336 f2baddf5 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/11/02 08:07 linux-5.15.y 72244eab0dad f00eed24 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/07/21 09:23 linux-5.15.y 7c6d66f0266f b88348e9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/04/27 10:23 linux-5.15.y c52b9710c83d 07b455f9 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/01/11 20:14 linux-5.15.y 26c690eff0a5 00f3cc59 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/08/29 10:32 linux-5.15.y 5ddfe5cc8716 7ba13a15 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/05/19 03:19 linux-5.15.y 9d6bde853685 3bb7af1d .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/03/26 04:43 linux-5.15.y 115472395b0a fbf0499a .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/14 11:06 linux-5.15.y f7347f400572 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/13 23:35 linux-5.15.y f7347f400572 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/11 12:12 linux-5.15.y f7347f400572 94486846 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/03/19 22:52 linux-5.15.y 0c935c049b5c e20d7b13 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/03/18 11:45 linux-5.15.y 0c935c049b5c ce3352cd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/25 21:25 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/25 14:49 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/22 02:53 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/18 05:46 linux-5.15.y c16c81c81336 429ea007 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 21:58 linux-5.15.y c16c81c81336 b27c2402 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 21:56 linux-5.15.y c16c81c81336 b27c2402 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 07:05 linux-5.15.y c16c81c81336 f2baddf5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/22 12:28 linux-5.15.y 4735586da88e da72ac06 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/17 23:31 linux-5.15.y 4735586da88e 953d1c45 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/17 22:04 linux-5.15.y 4735586da88e 953d1c45 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/06 05:02 linux-5.15.y 91786f140358 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/02 23:46 linux-5.15.y 91786f140358 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/12/15 11:43 linux-5.15.y 963e654022cc 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/12/14 05:43 linux-5.15.y 0a51d2d4527b 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/11/02 01:05 linux-5.15.y 72244eab0dad f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/11/01 11:37 linux-5.15.y 72244eab0dad 96eb609f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/10/27 11:57 linux-5.15.y 74cdd62cb470 65e8686b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/10/25 22:23 linux-5.15.y 74cdd62cb470 045e728d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/09/21 17:16 linux-5.15.y 3a5928702e71 6f888b75 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/09/16 13:55 linux-5.15.y 3a5928702e71 08d8a733 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/09/01 09:57 linux-5.15.y fa93fa65db6e 1eda0d14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/08/25 21:11 linux-5.15.y fa93fa65db6e d7d32352 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/08/25 11:59 linux-5.15.y fa93fa65db6e d7d32352 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/08/16 19:23 linux-5.15.y 7e89efd3ae1c e1c76ab2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/08/11 18:31 linux-5.15.y 7e89efd3ae1c 6f4edef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/08/09 01:19 linux-5.15.y 7e89efd3ae1c 61405512 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/08/03 06:57 linux-5.15.y 7e89efd3ae1c 1786a2a8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/07/14 10:16 linux-5.15.y f45bea23c39c eaeb5c15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/07/05 21:50 linux-5.15.y f45bea23c39c 2a40360c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/06/11 15:51 linux-5.15.y c61bd26ae81a b7d9eb04 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/05/18 17:09 linux-5.15.y 83655231580b c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/05/09 13:32 linux-5.15.y 284087d4f7d5 05079661 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/05/06 03:49 linux-5.15.y 284087d4f7d5 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/05/05 01:10 linux-5.15.y 284087d4f7d5 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/04/27 20:54 linux-5.15.y b925f60c6ee7 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/04/27 17:56 linux-5.15.y b925f60c6ee7 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/04/27 15:52 linux-5.15.y c52b9710c83d 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/04/27 09:41 linux-5.15.y c52b9710c83d 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/03/10 11:13 linux-5.15.y abddfcf701a5 5205ef30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
* Struck through repros no longer work on HEAD.