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From 1f0d30e5c9678eadf94739eb9bc088444cece3fc Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 4 Jun 2025 10:30:36 +0800
Subject: ACPI: CPPC: Fix NULL pointer dereference when nosmp is used
From: Yunhui Cui <cuiyunhui@bytedance.com>
[ Upstream commit 15eece6c5b05e5f9db0711978c3e3b7f1a2cfe12 ]
With nosmp in cmdline, other CPUs are not brought up, leaving
their cpc_desc_ptr NULL. CPU0's iteration via for_each_possible_cpu()
dereferences these NULL pointers, causing panic.
Panic backtrace:
[ 0.401123] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b8
...
[ 0.403255] [<ffffffff809a5818>] cppc_allow_fast_switch+0x6a/0xd4
...
Kernel panic - not syncing: Attempted to kill init!
Fixes: 3cc30dd00a58 ("cpufreq: CPPC: Enable fast_switch")
Reported-by: Xu Lu <luxu.kernel@bytedance.com>
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Link: https://patch.msgid.link/20250604023036.99553-1-cuiyunhui@bytedance.com
[ rjw: New subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/acpi/cppc_acpi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 0e1fb97d5d763..504fe14c566e3 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -456,7 +456,7 @@ bool cppc_allow_fast_switch(void)
struct cpc_desc *cpc_ptr;
int cpu;
- for_each_possible_cpu(cpu) {
+ for_each_present_cpu(cpu) {
cpc_ptr = per_cpu(cpc_desc_ptr, cpu);
desired_reg = &cpc_ptr->cpc_regs[DESIRED_PERF];
if (!CPC_IN_SYSTEM_MEMORY(desired_reg) &&
--
2.39.5
|
