On Fri, Mar 12, 2021 at 3:30 AM Andy Lutomirski <luto@xxxxxxxxxx> wrote: > > Your warning is odd, but I see the bug. It's in KVM. Hi Andy, By "your" you mean "kernel", right? ;) > On Thu, Mar 11, 2021 at 4:37 PM syzbot > <syzbot+7d7013084f0a806f3786@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 05a59d79 Merge git://git.kernel.org:/pub/scm/linux/kernel/.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=16f493ead00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=750735fdbc630971 > > dashboard link: https://syzkaller.appspot.com/bug?extid=7d7013084f0a806f3786 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+7d7013084f0a806f3786@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ------------[ cut here ]------------ > > raw_local_irq_restore() called with IRQs enabled > > WARNING: CPU: 0 PID: 8412 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x1d/0x20 kernel/locking/irqflag-debug.c:10 > > Modules linked in: > > CPU: 0 PID: 8412 Comm: syz-fuzzer Not tainted 5.12.0-rc2-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > RIP: 0010:warn_bogus_irq_restore+0x1d/0x20 kernel/locking/irqflag-debug.c:10 > > The above makes sense, but WTH is the below: > > > Code: be ff cc cc cc cc cc cc cc cc cc cc cc 80 3d 11 d1 ad 04 00 74 01 c3 48 c7 c7 20 79 6b 89 c6 05 00 d1 ad 04 01 e8 75 5b be ff <0f> 0b c3 48 39 77 10 0f 84 97 00 00 00 66 f7 47 22 f0 ff 74 4b 48 > > RSP: 0000:ffffc9000185fac8 EFLAGS: 00010282 > > RAX: 0000000000000000 RBX: ffff8880194268a0 RCX: 0000000000000000 > > RBP: 0000000000000200 R08: 0000000000000000 R09: 0000000000000000 > > R13: ffffed1003284d14 R14: 0000000000000001 R15: ffff8880b9c36000 > > FS: 000000c00002ec90(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > > Call Trace: > > handle_mm_fault+0x1bc/0x7e0 mm/memory.c:4549 > > Code: 48 8d 05 97 25 3e 00 48 89 44 24 08 e8 6d 54 ea ff 90 e8 07 a1 ed ff eb a5 cc cc cc cc cc 8b 44 24 10 48 8b 4c 24 08 89 41 24 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 48 8b > > RAX: 00000000000047f6 RBX: 00000000000047f6 RCX: 0000000000d60000 > > RDX: 0000000000004c00 RSI: 0000000000d60000 RDI: 000000000181cad0 > > RBP: 000000c000301890 R08: 00000000000047f5 R09: 000000000059c5a0 > > R10: 000000c0004e2000 R11: 0000000000000020 R12: 00000000000000fa > > R13: 00aaaaaaaaaaaaaa R14: 000000000093f064 R15: 0000000000000038 > > Kernel panic - not syncing: panic_on_warn set ... > > CPU: 0 PID: 8412 Comm: syz-fuzzer Not tainted 5.12.0-rc2-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > Now we start reading here: > > > __dump_stack lib/dump_stack.c:79 [inline] > > dump_stack+0x141/0x1d7 lib/dump_stack.c:120 > > panic+0x306/0x73d kernel/panic.c:231 > > __warn.cold+0x35/0x44 kernel/panic.c:605 > > report_bug+0x1bd/0x210 lib/bug.c:195 > > handle_bug+0x3c/0x60 arch/x86/kernel/traps.c:239 > > exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:259 > > asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:575 > > RIP: 0010:warn_bogus_irq_restore+0x1d/0x20 kernel/locking/irqflag-debug.c:10 > > Code: be ff cc cc cc cc cc cc cc cc cc cc cc 80 3d 11 d1 ad 04 00 74 01 c3 48 c7 c7 20 79 6b 89 c6 05 00 d1 ad 04 01 e8 75 5b be ff <0f> 0b c3 48 39 77 10 0f 84 97 00 00 00 66 f7 47 22 f0 ff 74 4b 48 > > RSP: 0000:ffffc9000185fac8 EFLAGS: 00010282 > > RAX: 0000000000000000 RBX: ffff8880194268a0 RCX: 0000000000000000 > > RDX: ffff88802f7b2400 RSI: ffffffff815b4435 RDI: fffff5200030bf4b > > RBP: 0000000000000200 R08: 0000000000000000 R09: 0000000000000000 > > R10: ffffffff815ad19e R11: 0000000000000000 R12: 0000000000000003 > > R13: ffffed1003284d14 R14: 0000000000000001 R15: ffff8880b9c36000 > > kvm_wait arch/x86/kernel/kvm.c:860 [inline] > > and there's the bug: > > /* > * halt until it's our turn and kicked. Note that we do safe halt > * for irq enabled case to avoid hang when lock info is overwritten > * in irq spinlock slowpath and no spurious interrupt occur to save us. > */ > if (arch_irqs_disabled_flags(flags)) > halt(); > else > safe_halt(); > > out: > local_irq_restore(flags); > } > > The safe_halt path is bogus. It should just return instead of > restoring the IRQ flags. I think this should be fixed already by: https://patchwork.kernel.org/project/kvm/patch/1614057902-23774-1-git-send-email-wanpengli@xxxxxxxxxxx/ #syz fix: x86/kvm: Fix broken irq restoration in kvm_wait
