linux-kernel - [PATCH 2/2] staging/sep: Check pointers before dereferencing (fix smatch warning)

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Date:	Tue, 19 Feb 2013 13:07:28 +0100
From:	Peter Huewe <peterhuewe@....de>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Devendra Naga <devendra.aaru@...il.com>,
	Peter Huewe <peterhuewe@....de>,
	"Robert P. J. Day" <rpjday@...shcourse.ca>,
	Joe Perches <joe@...ches.com>, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] staging/sep: Check pointers before dereferencing (fix smatch warning)

smatch complains about two dereferenced before check issues:

sep_main.c:2898 sep_free_dma_tables_and_dcb() warn: variable dereferenced before check
'dma_ctx' (see line 2885)
sep_main.c:2898 sep_free_dma_tables_and_dcb() warn: variable dereferenced before check
'*dma_ctx' (see line 2885)

-> Move the checks to the top, but keep the semantics.

Signed-off-by: Peter Huewe <peterhuewe@....de>
---
 drivers/staging/sep/sep_main.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/sep/sep_main.c b/drivers/staging/sep/sep_main.c
index 366d56b..f5b7341 100644
--- a/drivers/staging/sep/sep_main.c
+++ b/drivers/staging/sep/sep_main.c
@@ -2880,6 +2880,8 @@ static int sep_free_dma_tables_and_dcb(struct sep_device *sep, bool isapplet,
 
 	dev_dbg(&sep->pdev->dev, "[PID%d] sep_free_dma_tables_and_dcb\n",
 					current->pid);
+	if (!dma_ctx || !*dma_ctx) /* nothing to be done here*/
+		return 0;
 
 	if (((*dma_ctx)->secure_dma == false) && (isapplet == true)) {
 		dev_dbg(&sep->pdev->dev, "[PID%d] handling applet\n",
@@ -2895,8 +2897,7 @@ static int sep_free_dma_tables_and_dcb(struct sep_device *sep, bool isapplet,
 		 * Go over each DCB and see if
 		 * tail pointer must be updated
 		 */
-		for (i = 0; dma_ctx && *dma_ctx &&
-			i < (*dma_ctx)->nr_dcb_creat; i++, dcb_table_ptr++) {
+		for (i = 0; i < (*dma_ctx)->nr_dcb_creat; i++, dcb_table_ptr++) {
 			if (dcb_table_ptr->out_vr_tail_pt) {
 				pt_hold = (unsigned long)dcb_table_ptr->
 					out_vr_tail_pt;
-- 
1.7.8.6

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