Patch "i2c: bcm2835: Avoid possible NULL ptr dereference" has been added to the 4.10-stable tree

Patch "i2c: bcm2835: Avoid possible NULL ptr dereference" has been added to the 4.10-stable tree

[gregkh]

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

    i2c: bcm2835: Avoid possible NULL ptr dereference

to the 4.10-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-bcm2835-avoid-possible-null-ptr-dereference.patch
and it can be found in the queue-4.10 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 ababb08938df7ac245d30a58b95b94ecf8dc04fc Mon Sep 17 00:00:00 2001
From: Stefan Wahren <stefan.wahren@i2se.com>
Date: Thu, 16 Feb 2017 21:20:45 +0000
Subject: i2c: bcm2835: Avoid possible NULL ptr dereference
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Stefan Wahren <stefan.wahren@i2se.com>

commit ababb08938df7ac245d30a58b95b94ecf8dc04fc upstream.

Since commit e2474541032d ("bcm2835: Fix hang for writing messages
larger than 16 bytes") the interrupt handler is prone to a possible
NULL pointer dereference. This could happen if an interrupt fires
before curr_msg is set by bcm2835_i2c_xfer_msg() and randomly occurs
on the RPi 3. Even this is an unexpected behavior the driver must
handle that with an error instead of a crash.

Reported-by: Peter Robinson <pbrobinson@gmail.com>
Fixes: e2474541032d ("bcm2835: Fix hang for writing messages larger than 16 bytes")
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-bcm2835.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -195,7 +195,9 @@ static irqreturn_t bcm2835_i2c_isr(int t
 	}
 
 	if (val & BCM2835_I2C_S_DONE) {
-		if (i2c_dev->curr_msg->flags & I2C_M_RD) {
+		if (!i2c_dev->curr_msg) {
+			dev_err(i2c_dev->dev, "Got unexpected interrupt (from firmware?)\n");
+		} else if (i2c_dev->curr_msg->flags & I2C_M_RD) {
 			bcm2835_drain_rxfifo(i2c_dev);
 			val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
 		}


Patches currently in stable-queue which might be from stefan.wahren@i2se.com are

queue-4.10/i2c-bcm2835-avoid-possible-null-ptr-dereference.patch