Fix a number of problems in mstarddc_spi.c

Coverity has brought up the following problems:

mstarddc_spi_send_command():
 - CID 1270702: bad comparison of malloced pointer 'cmd'.
 - CID 1270701: a NULL pointer dereference possible because of above.

Simply checking the return value of malloc in a valid way fixes both problems.

mstarddc_spi_init():
 - CID 1270699 and 1270700: Memory leak of i2c_device.

This patch revamps the function in various ways to fix these issues and some
other irritating bits.
It reduces scopes of variables where possible, pushes the code towards our
coding standards and introduces a label-based resource cleanup at the end.

Corresponding to flashrom svn r1885.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Alexandre Boeglin <alex@boeglin.org>

1 files changed, 28 insertions, 25 deletions

diff --git a/mstarddc_spi.c b/mstarddc_spi.c
index 0b41a1b74..809d69049 100644
--- a/mstarddc_spi.c
+++ b/mstarddc_spi.c
@@ -74,37 +74,37 @@ static int mstarddc_spi_shutdown(void *data)
 /* Returns 0 upon success, a negative number upon errors. */
 int mstarddc_spi_init(void)
 {
-	char *i2c_device;
-	char *i2c_address;
-	char *noreset;
+	int ret = 0;
 
 	// Get device, address from command-line
-	i2c_device = extract_programmer_param("dev");
-	if (i2c_device && strlen(i2c_device)) {
-		if ((i2c_address = strchr(i2c_device, ':'))) {
+	char *i2c_device = extract_programmer_param("dev");
+	if (i2c_device != NULL && strlen(i2c_device) > 0) {
+		char *i2c_address = strchr(i2c_device, ':');
+		if (i2c_address != NULL) {
 			*i2c_address = '\0';
 			i2c_address++;
 		}
-		if (!i2c_address || !strlen(i2c_address)) {
+		if (i2c_address == NULL || strlen(i2c_address) == 0) {
 			msg_perr("Error: no address specified.\n"
 				 "Use flashrom -p mstarddc_spi:dev=/dev/device:address.\n");
-			return -1;
+			ret = -1;
+			goto out;
 		}
-		mstarddc_addr = strtol(i2c_address, NULL, 16);
+		mstarddc_addr = strtol(i2c_address, NULL, 16); // FIXME: error handling
 	} else {
 		msg_perr("Error: no device specified.\n"
 			 "Use flashrom -p mstarddc_spi:dev=/dev/device:address.\n");
-		return -1;
+		ret = -1;
+		goto out;
 	}
-	msg_pinfo("Info: Will try to use device %s and address 0x%02x.\n",
-		  i2c_device, mstarddc_addr);
+	msg_pinfo("Info: Will try to use device %s and address 0x%02x.\n", i2c_device, mstarddc_addr);
 
 	// Get noreset=1 option from command-line
-	if ((noreset = extract_programmer_param("noreset"))
-	    && noreset[0] == '1')
+	char *noreset = extract_programmer_param("noreset");
+	if (noreset != NULL && noreset[0] == '1')
 		mstarddc_doreset = 0;
-	msg_pinfo("Info: WILL %sreset the device at the end.\n",
-		  mstarddc_doreset ? "" : "NOT ");
+	free(noreset);
+	msg_pinfo("Info: Will %sreset the device at the end.\n", mstarddc_doreset ? "" : "NOT ");
 	// Open device
 	if ((mstarddc_fd = open(i2c_device, O_RDWR)) < 0) {
 		switch (errno) {
@@ -119,16 +119,17 @@ int mstarddc_spi_init(void)
 				 i2c_device);
 			break;
 		default:
-			msg_perr("Error opening %s: errno %d.\n",
-				 i2c_device, errno);
+			msg_perr("Error opening %s: %s.\n", i2c_device, strerror(errno));
 		}
-		return -1;
+		ret = -1;
+		goto out;
 	}
 	// Set slave address
 	if (ioctl(mstarddc_fd, I2C_SLAVE, mstarddc_addr) < 0) {
 		msg_perr("Error setting slave address 0x%02x: errno %d.\n",
 			 mstarddc_addr, errno);
-		return -1;
+		ret = -1;
+		goto out;
 	}
 	// Enable ISP mode
 	uint8_t cmd[5] = { 'M', 'S', 'T', 'A', 'R' };
@@ -141,7 +142,8 @@ int mstarddc_spi_init(void)
 			msg_perr("Error enabling ISP mode: errno %d & %d.\n"
 				 "Please check that device (%s) and address (0x%02x) are correct.\n",
 				 enable_err, errno, i2c_device, mstarddc_addr);
-			return -1;
+			ret = -1;
+			goto out;
 		}
 	}
 	// Register shutdown function
@@ -149,7 +151,9 @@ int mstarddc_spi_init(void)
 
 	// Register programmer
 	register_spi_master(&spi_master_mstarddc);
-	return 0;
+out:
+	free(i2c_device);
+	return ret;
 }
 
 /* Returns 0 upon success, a negative number upon errors. */
@@ -160,9 +164,8 @@ static int mstarddc_spi_send_command(struct flashctx *flash,
 				     unsigned char *readarr)
 {
 	int ret = 0;
-	uint8_t *cmd;
-
-	if ((cmd = malloc((writecnt + 1) * sizeof(uint8_t))) < 0) {
+	uint8_t *cmd = malloc((writecnt + 1) * sizeof(uint8_t));
+	if (cmd == NULL) {
 		msg_perr("Error allocating memory: errno %d.\n", errno);
 		ret = -1;
 	}