[3.13.y.z extended stable] Patch "btrfs: fix defrag 32-bit integer overflow" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    btrfs: fix defrag 32-bit integer overflow

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 87f4a90c0959ddba0cf0e285daf4365bbc4bda65 Mon Sep 17 00:00:00 2001
From: Justin Maggard <jmaggard10 at gmail.com>
Date: Tue, 21 Jan 2014 11:18:29 -0800
Subject: btrfs: fix defrag 32-bit integer overflow

commit c41570c9d29764f797fa35490d72b7395a0105c3 upstream.

When defragging a very large file, the cluster variable can wrap its 32-bit
signed int type and become negative, which eventually gets passed to
btrfs_force_ra() as a very large unsigned long value.  On 32-bit platforms,
this eventually results in an Oops from the SLAB allocator.

Change the cluster and max_cluster signed int variables to unsigned long to
match the readahead functions.  This also allows the min() comparison in
btrfs_defrag_file() to work as intended.

Signed-off-by: Josef Bacik <jbacik at fb.com>
Signed-off-by: Chris Mason <clm at fb.com>
Cc: Joseph Salisbury <joseph.salisbury at canonical.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/btrfs/ioctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9f831bb..043d6cd 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1011,7 +1011,7 @@ out:
 static int cluster_pages_for_defrag(struct inode *inode,
 				    struct page **pages,
 				    unsigned long start_index,
-				    int num_pages)
+				    unsigned long num_pages)
 {
 	unsigned long file_end;
 	u64 isize = i_size_read(inode);
@@ -1169,8 +1169,8 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 	int defrag_count = 0;
 	int compress_type = BTRFS_COMPRESS_ZLIB;
 	int extent_thresh = range->extent_thresh;
-	int max_cluster = (256 * 1024) >> PAGE_CACHE_SHIFT;
-	int cluster = max_cluster;
+	unsigned long max_cluster = (256 * 1024) >> PAGE_CACHE_SHIFT;
+	unsigned long cluster = max_cluster;
 	u64 new_align = ~((u64)128 * 1024 - 1);
 	struct page **pages = NULL;

--
1.9.1