linux-kernel - [PATCH 4.17 168/336] media: smiapp: fix timeout checking in smiapp_read

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Message-Id: <20180801165035.542952649@linuxfoundation.org>
Date:   Wed,  1 Aug 2018 18:48:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Ian King <colin.king@...onical.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.17 168/336] media: smiapp: fix timeout checking in smiapp_read_nvm

4.17-stable review patch.  If anyone has any objections, please let me know.

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

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

[ Upstream commit 7a2148dfda8001c983f0effd9afd8a7fa58e99c4 ]

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: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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
@@ -1001,7 +1001,7 @@ 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);
@@ -1012,11 +1012,10 @@ 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++) {