linux-kernel - [PATCH 3.16 059/366] media: smiapp: fix timeout checking in smiapp_read

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Date:   Sun, 11 Nov 2018 19:49:05 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Mauro Carvalho Chehab" <mchehab+samsung@...nel.org>,
        "Sakari Ailus" <sakari.ailus@...ux.intel.com>,
        "Colin Ian King" <colin.king@...onical.com>
Subject: [PATCH 3.16 059/366] media: smiapp: fix timeout checking in
 smiapp_read_nvm

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit 7a2148dfda8001c983f0effd9afd8a7fa58e99c4 upstream.

The current code decrements the timeout counter i and the end of
each loop i is incremented, so the check for timeout will always
be false and hence the timeout mechanism is just a dead code path.
Potentially, if the RD_READY bit is not set, we could end up in
an infinite loop.

Fix this so the timeout starts from 1000 and decrements to zero,
if at the end of the loop i is zero we have a timeout condition.

Detected by CoverityScan, CID#1324008 ("Logically dead code")

Fixes: ccfc97bdb5ae ("[media] smiapp: Add driver")

Signed-off-by: Colin Ian King <colin.king@...onical.com>
Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/i2c/smiapp/smiapp-core.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/drivers/media/i2c/smiapp/smiapp-core.c
+++ b/drivers/media/i2c/smiapp/smiapp-core.c
@@ -899,7 +899,7 @@ static int smiapp_read_nvm(struct smiapp
 		if (rval)
 			goto out;
 
-		for (i = 0; i < 1000; i++) {
+		for (i = 1000; i > 0; i--) {
 			rval = smiapp_read(
 				sensor,
 				SMIAPP_REG_U8_DATA_TRANSFER_IF_1_STATUS, &s);
@@ -910,11 +910,10 @@ static int smiapp_read_nvm(struct smiapp
 			if (s & SMIAPP_DATA_TRANSFER_IF_1_STATUS_RD_READY)
 				break;
 
-			if (--i == 0) {
-				rval = -ETIMEDOUT;
-				goto out;
-			}
-
+		}
+		if (!i) {
+			rval = -ETIMEDOUT;
+			goto out;
 		}
 
 		for (i = 0; i < SMIAPP_NVM_PAGE_SIZE; i++) {