linux-kernel - [PATCH] ACPI / CPPC: remove initial assignment of pcc_ss

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Date:   Fri,  8 Dec 2017 23:59:49 +0000
From:   Colin King <colin.king@...onical.com>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ACPI / CPPC: remove initial assignment of pcc_ss_data

From: Colin Ian King <colin.king@...onical.com>

The initialization of pcc_ss_data from pcc_data[pcc_ss_id] before
pcc_ss_id is being range checked could lead to an out-of-bounds array
read.  This very same initialization is also being performed after
the range check on pcc_ss_id, so we can just remove this problematic
and also redundant assignment to fix the issue.

Detected by cppcheck:
warning: Value stored to 'pcc_ss_data' during its initialization is never
read

Fixes: commit 85b1407bf6d2 ("ACPI / CPPC: Make CPPC ACPI driver aware of PCC subspace IDs")
Signed-off-by: Colin Ian King <colin.king@...onical.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 30e84cc600ae..06ea4749ebd9 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1171,7 +1171,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
 	struct cpc_register_resource *desired_reg;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
-	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
+	struct cppc_pcc_data *pcc_ss_data;
 	int ret = 0;
 
 	if (!cpc_desc || pcc_ss_id < 0) {
-- 
2.14.1