Patch "tpm_tis: 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_tis: 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_tis-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 12:32:06 -0800
Subject: tpm_tis: fix potential buffer overruns caused by bit glitches on the bus

From: Jeremy Boone <[email protected]>

commit 6bb320ca4a4a7b5b3db8c8d7250cc40002046878 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_tis.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -283,7 +283,8 @@ static int recv_data(struct tpm_chip *ch
 static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	int size = 0;
-	int expected, status;
+	int status;
+	u32 expected;
 
 	if (count < TPM_HEADER_SIZE) {
 		size = -EIO;

@@ -298,7 +299,7 @@ static int tpm_tis_recv(struct tpm_chip
 	}
 
 	expected = be32_to_cpu(*(__be32 *) (buf + 2));
-	if (expected > count) {
+	if (expected > count || expected < TPM_HEADER_SIZE) {
 		size = -EIO;
 		goto out;
 	}

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

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