[PATCH 4.15 011/122] tpm_i2c_nuvoton: fix potential buffer overruns caused by bit glitches on the bus

[Greg Kroah-Hartman]

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

--

From: Jeremy Boone 

commit f9d4d9b5a5ef2f017bc344fb65a58a902517173b upstream.

Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips.  In all the
driver _recv() functions, we need to use a u32 to unmarshal the
response size, otherwise a bit flip of the 31st bit would cause the
expected variable to go negative, which would then try to read a huge
amount of data.  Also sanity check that the expected amount of data is
large enough for the TPM header.

Signed-off-by: Jeremy Boone 
Cc: sta...@vger.kernel.org
Signed-off-by: James Bottomley 
Reviewed-by: Jarkko Sakkinen 
Signed-off-by: Jarkko Sakkinen 
Signed-off-by: James Morris 
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/char/tpm/tpm_i2c_nuvoton.c |8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/char/tpm/tpm_i2c_nuvoton.c
+++ b/drivers/char/tpm/tpm_i2c_nuvoton.c
@@ -281,7 +281,11 @@ static int i2c_nuvoton_recv(struct tpm_c
struct device *dev = chip->dev.parent;
struct i2c_client *client = to_i2c_client(dev);
s32 rc;
-   int expected, status, burst_count, retries, size = 0;
+   int status;
+   int burst_count;
+   int retries;
+   int size = 0;
+   u32 expected;
 
if (count < TPM_HEADER_SIZE) {
i2c_nuvoton_ready(chip);/* return to idle */
@@ -323,7 +327,7 @@ static int i2c_nuvoton_recv(struct tpm_c
 * to machine native
 */
expected = be32_to_cpu(*(__be32 *) (buf + 2));
-   if (expected > count) {
+   if (expected > count || expected < size) {
dev_err(dev, "%s() expected > count\n", __func__);
size = -EIO;
continue;

[PATCH 4.15 011/122] tpm_i2c_nuvoton: fix potential buffer overruns caused by bit glitches on the bus

[Greg Kroah-Hartman]

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

--

From: Jeremy Boone 

commit f9d4d9b5a5ef2f017bc344fb65a58a902517173b upstream.

Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips.  In all the
driver _recv() functions, we need to use a u32 to unmarshal the
response size, otherwise a bit flip of the 31st bit would cause the
expected variable to go negative, which would then try to read a huge
amount of data.  Also sanity check that the expected amount of data is
large enough for the TPM header.

Signed-off-by: Jeremy Boone 
Cc: sta...@vger.kernel.org
Signed-off-by: James Bottomley 
Reviewed-by: Jarkko Sakkinen 
Signed-off-by: Jarkko Sakkinen 
Signed-off-by: James Morris 
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/char/tpm/tpm_i2c_nuvoton.c |8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/char/tpm/tpm_i2c_nuvoton.c
+++ b/drivers/char/tpm/tpm_i2c_nuvoton.c
@@ -281,7 +281,11 @@ static int i2c_nuvoton_recv(struct tpm_c
struct device *dev = chip->dev.parent;
struct i2c_client *client = to_i2c_client(dev);
s32 rc;
-   int expected, status, burst_count, retries, size = 0;
+   int status;
+   int burst_count;
+   int retries;
+   int size = 0;
+   u32 expected;
 
if (count < TPM_HEADER_SIZE) {
i2c_nuvoton_ready(chip);/* return to idle */
@@ -323,7 +327,7 @@ static int i2c_nuvoton_recv(struct tpm_c
 * to machine native
 */
expected = be32_to_cpu(*(__be32 *) (buf + 2));
-   if (expected > count) {
+   if (expected > count || expected < size) {
dev_err(dev, "%s() expected > count\n", __func__);
size = -EIO;
continue;