patch "carl9170: fix debugfs crashes" added to driver-core-testing

[<gregkh@linuxfoundation.org>]

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

    carl9170: fix debugfs crashes

to my driver-core git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-testing branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will be merged to the driver-core-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


>From 6ee6d1cb391ca85b419f8d18bdfb1f020a5e859c Mon Sep 17 00:00:00 2001
From: Christian Lamparter <chunkeey@googlemail.com>
Date: Wed, 21 Sep 2016 18:49:36 +0200
Subject: carl9170: fix debugfs crashes

Ben Greear reported:
> I see lots of instability as soon as I load up the carl9710 NIC.
> My application is going to be poking at it's debugfs files...
>
> BUG: KASAN: slab-out-of-bounds in carl9170_debugfs_read+0xd5/0x2a0
> [carl9170] at addr 0xffff8801bc1208b0
> Read of size 8 by task btserver/5888
> =======================================================================
> BUG kmalloc-256 (Tainted: G        W      ): kasan: bad access detected
> -----------------------------------------------------------------------
>
> INFO: Allocated in seq_open+0x50/0x100 age=2690 cpu=2 pid=772
>...

This breakage was caused by the introduction of intermediate
fops in debugfs by commit 9fd4dcece43a
("debugfs: prevent access to possibly dead file_operations at file open")

Thankfully, the original/real fops are still available in d_fsdata.

Reported-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Cc: stable <stable@vger.kernel.org> # 4.7+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/wireless/ath/carl9170/debug.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/carl9170/debug.c b/drivers/net/wireless/ath/carl9170/debug.c
index 6808db433283..ec3a64e5d2bb 100644
--- a/drivers/net/wireless/ath/carl9170/debug.c
+++ b/drivers/net/wireless/ath/carl9170/debug.c
@@ -75,7 +75,8 @@ static ssize_t carl9170_debugfs_read(struct file *file, char __user *userbuf,
 
 	if (!ar)
 		return -ENODEV;
-	dfops = container_of(file->f_op, struct carl9170_debugfs_fops, fops);
+	dfops = container_of(debugfs_real_fops(file),
+			     struct carl9170_debugfs_fops, fops);
 
 	if (!dfops->read)
 		return -ENOSYS;
@@ -127,7 +128,8 @@ static ssize_t carl9170_debugfs_write(struct file *file,
 
 	if (!ar)
 		return -ENODEV;
-	dfops = container_of(file->f_op, struct carl9170_debugfs_fops, fops);
+	dfops = container_of(debugfs_real_fops(file),
+			     struct carl9170_debugfs_fops, fops);
 
 	if (!dfops->write)
 		return -ENOSYS;
-- 
2.10.0