linux-kernel - [PATCH 1/2] tpm/tpm_ppi: Do not compare strcmp(a,b) == -1

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Message-Id: <1383093628-31580-1-git-send-email-peterhuewe@gmx.de>
Date:	Wed, 30 Oct 2013 01:40:27 +0100
From:	Peter Huewe <peterhuewe@....de>
To:	Peter Huewe <peterhuewe@....de>
Cc:	Ashley Lai <ashley@...leylai.com>, Rajiv Andrade <mail@...jiv.net>,
	Marcel Selhorst <tpmdd@...horst.net>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	Xiaoyan Zhang <xiaoyan.zhang@...el.com>,
	Gang Wei <gang.wei@...el.com>, stable@...r.kernel.org
Subject: [PATCH 1/2] tpm/tpm_ppi: Do not compare strcmp(a,b) == -1

strcmp does return the difference between two strings not only -1,0,1
consequently
 if (strcmp (a,b) == -1)
might lead to taking the wrong branch

-> compare with <= instead.

This also makes the code/behavior compliant with its comments.
(e.g. if PPI Version is 1.0)

Fixes Coverity complaints:
CID: 741083 Misuse of memcmp-style function
CID: 741084 Misuse of memcmp-style function
CID: 741085 Misuse of memcmp-style function

Cc: stable@...r.kernel.org
Signed-off-by: Peter Huewe <peterhuewe@....de>
---
 drivers/char/tpm/tpm_ppi.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index 8e562dc..8b2e05a 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -169,7 +169,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
 	 * is updated with function index from SUBREQ to SUBREQ2 since PPI
 	 * version 1.1
 	 */
-	if (strcmp(version, "1.1") == -1)
+	if (strcmp(version, "1.1") <= -1)
 		params[2].integer.value = TPM_PPI_FN_SUBREQ;
 	else
 		params[2].integer.value = TPM_PPI_FN_SUBREQ2;
@@ -179,7 +179,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
 	 * string/package type. For PPI version 1.0 and 1.1, use buffer type
 	 * for compatibility, and use package type since 1.2 according to spec.
 	 */
-	if (strcmp(version, "1.2") == -1) {
+	if (strcmp(version, "1.2") <= -1) {
 		params[3].type = ACPI_TYPE_BUFFER;
 		params[3].buffer.length = sizeof(req);
 		sscanf(buf, "%d", &req);
@@ -245,7 +245,7 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
 	 * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
 	 * compatibility, define params[3].type as buffer, if PPI version < 1.2
 	 */
-	if (strcmp(version, "1.2") == -1) {
+	if (strcmp(version, "1.2") <= -1) {
 		params[3].type = ACPI_TYPE_BUFFER;
 		params[3].buffer.length =  0;
 		params[3].buffer.pointer = NULL;
@@ -387,7 +387,7 @@ static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
 	kfree(output.pointer);
 	output.length = ACPI_ALLOCATE_BUFFER;
 	output.pointer = NULL;
-	if (strcmp(version, "1.2") == -1)
+	if (strcmp(version, "1.2") <= -1)
 		return -EPERM;
 
 	params[2].integer.value = TPM_PPI_FN_GETOPR;
-- 
1.7.8.6

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