Patch "md: use kzalloc() when bitmap is disabled" has been added to the 3.10-stable tree

Patch "md: use kzalloc() when bitmap is disabled" has been added to the 3.10-stable tree

[gregkh]

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

    md: use kzalloc() when bitmap is disabled

to the 3.10-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:
     md-use-kzalloc-when-bitmap-is-disabled.patch
and it can be found in the queue-3.10 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 b6878d9e03043695dbf3fa1caa6dfc09db225b16 Mon Sep 17 00:00:00 2001
From: Benjamin Randazzo <benjamin@randazzo.fr>
Date: Sat, 25 Jul 2015 16:36:50 +0200
Subject: md: use kzalloc() when bitmap is disabled

From: Benjamin Randazzo <benjamin@randazzo.fr>

commit b6878d9e03043695dbf3fa1caa6dfc09db225b16 upstream.

In drivers/md/md.c get_bitmap_file() uses kmalloc() for creating a
mdu_bitmap_file_t called "file".

5769         file = kmalloc(sizeof(*file), GFP_NOIO);
5770         if (!file)
5771                 return -ENOMEM;

This structure is copied to user space at the end of the function.

5786         if (err == 0 &&
5787             copy_to_user(arg, file, sizeof(*file)))
5788                 err = -EFAULT

But if bitmap is disabled only the first byte of "file" is initialized
with zero, so it's possible to read some bytes (up to 4095) of kernel
space memory from user space. This is an information leak.

5775         /* bitmap disabled, zero the first byte and copy out */
5776         if (!mddev->bitmap_info.file)
5777                 file->pathname[0] = '\0';

Signed-off-by: Benjamin Randazzo <benjamin@randazzo.fr>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/md.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5628,9 +5628,9 @@ static int get_bitmap_file(struct mddev
 	int err = -ENOMEM;
 
 	if (md_allow_write(mddev))
-		file = kmalloc(sizeof(*file), GFP_NOIO);
+		file = kzalloc(sizeof(*file), GFP_NOIO);
 	else
-		file = kmalloc(sizeof(*file), GFP_KERNEL);
+		file = kzalloc(sizeof(*file), GFP_KERNEL);
 
 	if (!file)
 		goto out;


Patches currently in stable-queue which might be from benjamin@randazzo.fr are

queue-3.10/md-use-kzalloc-when-bitmap-is-disabled.patch