From: Yunhui Cui <cuiyunhui@bytedance.com> stable inclusion from stable-v6.6.94 commit c6dad167aade4bf0bef9130f2f149f4249fc4ad0 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICJTC8 CVE: CVE-2025-38113 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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> Signed-off-by: Zeng Heng <zengheng4@huawei.com> --- 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 95ecc6281dd6..bc4917c3c29a 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -461,7 +461,7 @@ 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) && -- 2.25.1