"power" module can be loaded if it is not amd processor.
And user cannot unload it after loaded it. The following call trace generated
when tried to unload it.
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: __list_del_entry_valid+0x29/0x90
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 1 PID: 26046 Comm: modprobe Not tainted 4.14.13-300.fc27.x86_64 #1
Hardware name: Xen HVM domU, BIOS 4.9.1 12/12/2017
task: ffff9a138f8dddc0 task.stack: ffffb0ec41cbc000
RIP: 0010:__list_del_entry_valid+0x29/0x90
Call Trace:
perf_pmu_unregister+0x25/0xf0
amd_power_pmu_exit+0x1c/0xd23 [power]
SyS_delete_module+0x1a8/0x2b0
? exit_to_usermode_loop+0x8f/0xb0
entry_SYSCALL_64_fastpath+0x20/0x83
RIP: 0033:0x7fb67d78e5c7
Signed-off-by: Xiao Liang <xili...@redhat.com>
---
arch/x86/events/amd/power.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/power.c b/arch/x86/events/amd/power.c
index a6eee5ac4f58..2aefacf5c5b2 100644
--- a/arch/x86/events/amd/power.c
+++ b/arch/x86/events/amd/power.c
@@ -277,7 +277,7 @@ static int __init amd_power_pmu_init(void)
int ret;
if (!x86_match_cpu(cpu_match))
- return 0;
+ return -ENODEV;
if (!boot_cpu_has(X86_FEATURE_ACC_POWER))
return -ENODEV;
--
2.14.3
