[PATCH] platform/x86/intel/pmc: validate LPM mode without stale index

[Yousef Alhouseen]

pmc_lpm_mode_write() compares the requested mode with the loop variable
after pmc_for_each_mode().  If no low-power modes are enabled,
the loop never assigns that variable and the comparison reads an
uninitialized value.

Track a successful match explicitly, including the empty-mode case.

Signed-off-by: Yousef Alhouseen <alhouseenyousef@xxxxxxxxx>
---
 drivers/platform/x86/intel/pmc/core.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
index 9f77c0716e59..9833df172d4e 100644
--- a/drivers/platform/x86/intel/pmc/core.c
+++ b/drivers/platform/x86/intel/pmc/core.c
@@ -1147,6 +1147,7 @@ static ssize_t pmc_core_lpm_latch_mode_write(struct file *file,
 	struct pmc_dev *pmcdev = s->private;
 	struct pmc *pmc = pmcdev->pmcs[PMC_IDX_MAIN];
 	bool clear = false, c10 = false;
+	bool mode_enabled = false;
 	unsigned char buf[8];
 	int mode;
 	u32 reg;
@@ -1167,11 +1168,16 @@ static ssize_t pmc_core_lpm_latch_mode_write(struct file *file,
 	mode = sysfs_match_string(pmc_lpm_modes, buf);
 
 	/* Check string matches enabled mode */
-	pmc_for_each_mode(m, pmc)
-		if (mode == m)
-			break;
+	if (mode >= 0) {
+		pmc_for_each_mode(m, pmc) {
+			if (mode == m) {
+				mode_enabled = true;
+				break;
+			}
+		}
+	}
 
-	if (mode != m || mode < 0) {
+	if (!mode_enabled) {
 		if (sysfs_streq(buf, "clear"))
 			clear = true;
 		else if (sysfs_streq(buf, "c10"))
-- 
2.54.0