Patch "carl9170: fix debugfs crashes" has been added to the 4.8-stable tree

Patch "carl9170: fix debugfs crashes" has been added to the 4.8-stable tree

[gregkh]

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

    carl9170: fix debugfs crashes

to the 4.8-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:
     carl9170-fix-debugfs-crashes.patch
and it can be found in the queue-4.8 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 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

From: Christian Lamparter <chunkeey@googlemail.com>

commit 6ee6d1cb391ca85b419f8d18bdfb1f020a5e859c upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/ath/carl9170/debug.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- 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(str
 
 	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(st
 
 	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;


Patches currently in stable-queue which might be from chunkeey@googlemail.com are

queue-4.8/b43-fix-debugfs-crash.patch
queue-4.8/carl9170-fix-debugfs-crashes.patch
queue-4.8/b43legacy-fix-debugfs-crash.patch
queue-4.8/debugfs-introduce-a-public-file_operations-accessor.patch