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

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 <[email protected]> know about it.

From: Stefan Wahren <[email protected]>
Date: Thu, 16 Feb 2017 21:20:45 +0000
Subject: i2c: bcm2835: Avoid possible NULL ptr dereference
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From: Stefan Wahren <[email protected]>

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.

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

@@ -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 [email protected] are

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