[PATCH 1/6] tpm/tpm_ppi: Do not compare strcmp(a,b) == -1

[PATCH 1/6] tpm/tpm_ppi: Do not compare strcmp(a,b) == -1

[Peter Huewe]

From: Peter Huewe <PeterHuewe@gmx.de>

Depending on the implementation strcmp might 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 < 0  instead,
which in any case is more canonical.

Cc: stable@vger.kernel.org
Signed-off-by: Peter Huewe <peterhuewe@gmx.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..18c5810 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") < 0)
 		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") < 0) {
 		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") < 0) {
 		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") < 0)
 		return -EPERM;
 
 	params[2].integer.value = TPM_PPI_FN_GETOPR;
-- 
1.7.5.4

[PATCH 2/6] tpm/tpm_ppi: Check return value of acpi_get_name

[Peter Huewe]

From: Peter Huewe <PeterHuewe@gmx.de>

If
 status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
fails for whatever reason and does not return AE_OK
 if (strstr(buffer.pointer, context) != NULL) {
does dereference a null pointer.

-> Check the return value and return the status to the caller

Found by coverity
Cc: stable@vger.kernel.org
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
---
 drivers/char/tpm/tpm_ppi.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index 18c5810..6ac9d27 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -30,6 +30,9 @@ static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
 	acpi_status status;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
+	if (ACPI_FAILURE(status))
+		return status;
+
 	if (strstr(buffer.pointer, context) != NULL) {
 		*return_value = handle;
 		kfree(buffer.pointer);
-- 
1.7.5.4

[PATCH 3/6] tpm/tpm_i2c_stm_st33: Check return code of get_burstcount

[Peter Huewe]

From: Peter Huewe <PeterHuewe@gmx.de>

The 'get_burstcount' function can in some circumstances 'return -EBUSY' which
in tpm_stm_i2c_send is stored in an 'u32 burstcnt'
thus converting the signed value into an unsigned value, resulting
in 'burstcnt' being huge.
Changing the type to u32 only does not solve the problem as the signed
value is converted to an unsigned in I2C_WRITE_DATA, resulting in the
same effect.

Thus
-> Change type of burstcnt to u32 (the return type of get_burstcount)
-> Add a check for the return value of 'get_burstcount' and propagate a
potential error.

This makes also sense in the 'I2C_READ_DATA' case, where the there is no
signed/unsigned conversion.

found by coverity
Cc: stable@vger.kernel.org
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
---
 drivers/char/tpm/tpm_i2c_stm_st33.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/drivers/char/tpm/tpm_i2c_stm_st33.c b/drivers/char/tpm/tpm_i2c_stm_st33.c
index a0d6ceb5..cf68403 100644
--- a/drivers/char/tpm/tpm_i2c_stm_st33.c
+++ b/drivers/char/tpm/tpm_i2c_stm_st33.c
@@ -410,6 +410,8 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 			     &chip->vendor.read_queue)
 	       == 0) {
 		burstcnt = get_burstcount(chip);
+		if (burstcnt < 0)
+			return burstcnt;
 		len = min_t(int, burstcnt, count - size);
 		I2C_READ_DATA(client, TPM_DATA_FIFO, buf + size, len);
 		size += len;
@@ -451,7 +453,8 @@ static irqreturn_t tpm_ioserirq_handler(int irq, void *dev_id)
 static int tpm_stm_i2c_send(struct tpm_chip *chip, unsigned char *buf,
 			    size_t len)
 {
-	u32 status, burstcnt = 0, i, size;
+	u32 status, i, size;
+	int burstcnt = 0;
 	int ret;
 	u8 data;
 	struct i2c_client *client;
@@ -482,6 +485,8 @@ static int tpm_stm_i2c_send(struct tpm_chip *chip, unsigned char *buf,
 
 	for (i = 0; i < len - 1;) {
 		burstcnt = get_burstcount(chip);
+		if (burstcnt < 0)
+			return burstcnt;
 		size = min_t(int, len - i - 1, burstcnt);
 		ret = I2C_WRITE_DATA(client, TPM_DATA_FIFO, buf, size);
 		if (ret < 0)
-- 
1.7.5.4