linux-kernel - [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20161024152226.2536749-1-arnd@arndb.de>
Date:   Mon, 24 Oct 2016 17:22:01 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Alison Schofield <amsfield22@...il.com>,
        linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case

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 <arnd@...db.de>
---
v2: handle failure for both affected reads instead of just the one
    we get a warning for
v2: do not retry on failure to avoid looping in case of permanent
    errors
---
 drivers/staging/iio/impedance-analyzer/ad5933.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
index 5eecf1cb1028..3892a7470410 100644
--- a/drivers/staging/iio/impedance-analyzer/ad5933.c
+++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
@@ -655,6 +655,7 @@ static void ad5933_work(struct work_struct *work)
 	__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_struct *work)
 		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_struct *work)
 	} 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_struct *work)
 		ad5933_cmd(st, AD5933_CTRL_INC_FREQ);
 		schedule_delayed_work(&st->work, st->poll_time_jiffies);
 	}
-
+out:
 	mutex_unlock(&indio_dev->mlock);
 }
 
-- 
2.9.0