Patch "tpm_i2c_nuvoton: fix potential buffer overruns caused by bit glitches on the bus" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

tpm_i2c_nuvoton: fix potential buffer overruns caused by bit glitches on the bus

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tpm_i2c_nuvoton-fix-potential-buffer-overruns-caused-by-bit-glitches-on-the-bus.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jeremy Boone <[email protected]>
Date: Thu, 8 Feb 2018 12:31:16 -0800
Subject: tpm_i2c_nuvoton: fix potential buffer overruns caused by bit glitches on the bus

From: Jeremy Boone <[email protected]>

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.

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

@@ -267,7 +267,11 @@ 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 */

@@ -309,7 +313,7 @@ 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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/tpm_i2c_nuvoton-fix-potential-buffer-overruns-caused-by-bit-glitches-on-the-bus.patch queue-4.4/tpm-st33zp24-fix-potential-buffer-overruns-caused-by-bit-glitches-on-the-bus.patch queue-4.4/tpm_i2c_infineon-fix-potential-buffer-overruns-caused-by-bit-glitches-on-the-bus.patch