Patch "i2c: ismt: Return EMSGSIZE for block reads with bogus length" has been added to the 4.12-stable tree

Patch "i2c: ismt: Return EMSGSIZE for block reads with bogus length" has been added to the 4.12-stable tree

[gregkh]

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

    i2c: ismt: Return EMSGSIZE for block reads with bogus length

to the 4.12-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:
     i2c-ismt-return-emsgsize-for-block-reads-with-bogus-length.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ba201c4f5ebe13d7819081756378777d8153f23e Mon Sep 17 00:00:00 2001
From: Stephen Douthit <stephend@adiengineering.com>
Date: Mon, 7 Aug 2017 17:11:00 -0400
Subject: i2c: ismt: Return EMSGSIZE for block reads with bogus length

From: Stephen Douthit <stephend@adiengineering.com>

commit ba201c4f5ebe13d7819081756378777d8153f23e upstream.

Compare the number of bytes actually seen on the wire to the byte
count field returned by the slave device.

Previously we just overwrote the byte count returned by the slave
with the real byte count and let the caller figure out if the
message was sane.

Signed-off-by: Stephen Douthit <stephend@adiengineering.com>
Tested-by: Dan Priamo <danp@adiengineering.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-ismt.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -341,8 +341,10 @@ static int ismt_process_desc(const struc
 			break;
 		case I2C_SMBUS_BLOCK_DATA:
 		case I2C_SMBUS_I2C_BLOCK_DATA:
+			if (desc->rxbytes != dma_buffer[0] + 1)
+				return -EMSGSIZE;
+
 			memcpy(data->block, dma_buffer, desc->rxbytes);
-			data->block[0] = desc->rxbytes - 1;
 			break;
 		}
 		return 0;


Patches currently in stable-queue which might be from stephend@adiengineering.com are

queue-4.12/i2c-ismt-don-t-duplicate-the-receive-length-for-block-reads.patch
queue-4.12/i2c-ismt-return-emsgsize-for-block-reads-with-bogus-length.patch