Patch "tpm: fix potential buffer overruns caused by bit glitches on the bus" has been added to the 4.9-stable tree

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

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

to the 4.9-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-fix-potential-buffer-overruns-caused-by-bit-glitches-on-the-bus.patch
and it can be found in the queue-4.9 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 12:28:08 -0800
Subject: tpm: fix potential buffer overruns caused by bit glitches on the bus

From: Jeremy Boone <[email protected]>

commit 3be23274755ee85771270a23af7691dc9b3a95db upstream.

Discrete TPMs are often connected over slow serial buses which, on some platforms, can have glitches causing bit flips. If a bit does flip it could cause an overrun if it's in one of the size parameters, so sanity check that we're not overrunning the provided buffer when doing a memcpy().

---
 drivers/char/tpm/tpm-interface.c |    5 +++++
 drivers/char/tpm/tpm2-cmd.c      |    6 ++++++
 2 files changed, 11 insertions(+)

@@ -1078,6 +1078,11 @@ int tpm_get_random(u32 chip_num, u8 *out
 			break;
 
 		recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
+		if (recd > num_bytes) {
+			total = -EFAULT;
+			break;
+		}
+
 		memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
 
 		dest += recd;

@@ -668,6 +668,11 @@ static int tpm2_unseal_cmd(struct tpm_ch
 	if (!rc) {
 		data_len = be16_to_cpup(
 			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
+		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE + 1) {
+			rc = -EFAULT;
+			goto out;
+		}
+
 		data = &buf.data[TPM_HEADER_SIZE + 6];
 
 		memcpy(payload->key, data, data_len - 1);

@@ -675,6 +680,7 @@ static int tpm2_unseal_cmd(struct tpm_ch
 		payload->migratable = data[data_len - 1];
 	}
 
+out:
 	tpm_buf_destroy(&buf);
 	return rc;
 }

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

queue-4.9/tpm-fix-potential-buffer-overruns-caused-by-bit-glitches-on-the-bus.patch