possible deadlock in console_lock_spinning_enable

[Rani Irawan]

Dear Linux maintainers and Syzkaller team,

We would like to report a bug found by our modified Syzkaller. This bug involves perf_event_open(), which triggers an Intel PMU event, causing an unchecked MSR access and a lockdep circular locking warning. The first visible error is:

unchecked MSR access error: WRMSR to 0x186

tried to write 0x00000001045106fb

intel_pmu_enable_event+0xd37/0x12a0 arch/x86/events/intel/core.c:3309

After that, printk emits the MSR warning while perf is still holding &ctx->lock, so lockdep reports:

WARNING: possible circular locking dependency detected

possible deadlock in console_lock_spinning_enable

Linux kernel commit: 4edcdefd4083ae04b1a5656f4be6cd83ae919ef4 (7.1.0-14063-g4edcdefd4083).

Attached to this email:

1. Kernel config
2. Syzkaller report
3. Repro program (in .c and .txt)

This is the command used to run the repro (please change “/path-to” to the actual path):

On one terminal:

• gcc -Wall -static -pthread repro-9c8.c -o repro-9c8
• KERNEL=/path-to/linux
• IMAGE=/path-to/image/bullseye.img
• SSHKEY=/path-to/image/bullseye.id_rsa
• PORT=10021
• qemu-system-x86_64 \
    -m 8192 \
    -smp 2 \
    -cpu host,migratable=off,pmu=on \
    -enable-kvm \
    -kernel $KERNEL/arch/x86/boot/bzImage \
    -append "console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0 nokaslr oops=panic panic_on_warn=1 panic=86400 enforcing=0 selinux=0" \
    -drive file=$IMAGE/bullseye.img,format=raw \
    -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:$PORT-:22 \
    -net nic,model=e1000 \
    -nographic \
    2>&1 | tee /path-to/repro-9c8-vm.log

On another terminal (set the $SSHKEY, $PORT):

• scp -P "$PORT" \
    -i "$SSHKEY" \
    -o StrictHostKeyChecking=no \
    -o UserKnownHostsFile=/dev/null \
    /path-to/repro-9c8 \
    ro...@127.0.0.1:/root/repro-9c8
• ssh -p "$PORT" \
    -i "$SSHKEY" \
    -o StrictHostKeyChecking=no \
    -o UserKnownHostsFile=/dev/null \
    ro...@127.0.0.1 \
    'chmod +x /root/repro-9c8 && sysctl -w kernel.perf_event_paranoid=-1 || true; /root/repro-9c8'

Please let me know if any additional information is needed.

Thank you and have a good day!

Best,

Rani