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Patch "staging: iio: ad5933: avoid uninitialized variable in error case" has been added to the 4.8-stable tree

PATCH [email protected] 1 participant 1 message Nov 15, 2016

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Stable branch Staging IIO Analog Devices IIO drivers +1 more subsystems
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This is a note to let you know that I've just added the patch titled

staging: iio: ad5933: avoid uninitialized variable in error case

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
staging-iio-ad5933-avoid-uninitialized-variable-in-error-case.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 34eee70a7b82b09dbda4cb453e0e21d460dae226 Mon Sep 17 00:00:00 2001

From: Arnd Bergmann <[email protected]>
Date: Mon, 24 Oct 2016 17:22:01 +0200
Subject: staging: iio: ad5933: avoid uninitialized variable in error case

From: Arnd Bergmann <[email protected]>

commit 34eee70a7b82b09dbda4cb453e0e21d460dae226 upstream.

The ad5933_i2c_read function returns an error code to indicate whether it could read data or not. However ad5933_work() ignores this return code and just accesses the data unconditionally, which gets detected by gcc as a possible bug:

drivers/staging/iio/impedance-analyzer/ad5933.c: In function 'ad5933_work':
drivers/staging/iio/impedance-analyzer/ad5933.c:649:16: warning: 'status' may be used uninitialized in this function [-Wmaybe-uninitialized]

This adds minimal error handling so we only evaluate the data if it was correctly read.

Link https://patchwork.kernel.org/patch/8110281/
Signed-off-by Arnd Bergmann <[email protected]>
Acked-by Lars-Peter Clausen <[email protected]>
Signed-off-by Jonathan Cameron <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/staging/iio/impedance-analyzer/ad5933.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)
drivers/staging/iio/impedance-analyzer/ad5933.c +10 -7
@@ -655,6 +655,7 @@ static void ad5933_work(struct work_stru
 	__be16 buf[2];
 	int val[2];
 	unsigned char status;
+	int ret;
 
 	mutex_lock(&indio_dev->mlock);
 	if (st->state == AD5933_CTRL_INIT_START_FREQ) {

@@ -662,19 +663,22 @@ static void ad5933_work(struct work_stru
 		ad5933_cmd(st, AD5933_CTRL_START_SWEEP);
 		st->state = AD5933_CTRL_START_SWEEP;
 		schedule_delayed_work(&st->work, st->poll_time_jiffies);
-		mutex_unlock(&indio_dev->mlock);
-		return;
+		goto out;
 	}
 
-	ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
+	ret = ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
+	if (ret)
+		goto out;
 
 	if (status & AD5933_STAT_DATA_VALID) {
 		int scan_count = bitmap_weight(indio_dev->active_scan_mask,
 					       indio_dev->masklength);
-		ad5933_i2c_read(st->client,
+		ret = ad5933_i2c_read(st->client,
 				test_bit(1, indio_dev->active_scan_mask) ?
 				AD5933_REG_REAL_DATA : AD5933_REG_IMAG_DATA,
 				scan_count * 2, (u8 *)buf);
+		if (ret)
+			goto out;
 
 		if (scan_count == 2) {
 			val[0] = be16_to_cpu(buf[0]);

@@ -686,8 +690,7 @@ static void ad5933_work(struct work_stru
 	} else {
 		/* no data available - try again later */
 		schedule_delayed_work(&st->work, st->poll_time_jiffies);
-		mutex_unlock(&indio_dev->mlock);
-		return;
+		goto out;
 	}
 
 	if (status & AD5933_STAT_SWEEP_DONE) {

@@ -700,7 +703,7 @@ static void ad5933_work(struct work_stru
 		ad5933_cmd(st, AD5933_CTRL_INC_FREQ);
 		schedule_delayed_work(&st->work, st->poll_time_jiffies);
 	}
-
+out:
 	mutex_unlock(&indio_dev->mlock);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/staging-iio-ad5933-avoid-uninitialized-variable-in-error-case.patch queue-4.8/dib0700-fix-nec-repeat-handling.patch