Patch "btrfs: fix int32 overflow in shrink_delalloc()." has been added to the 4.5-stable tree

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

btrfs: fix int32 overflow in shrink_delalloc().

to the 4.5-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:
btrfs-fix-int32-overflow-in-shrink_delalloc.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Adam Borowski <[email protected]>
Date: Sun, 8 May 2016 15:08:00 +0200
Subject: btrfs: fix int32 overflow in shrink_delalloc().

From: Adam Borowski <[email protected]>

commit 8eb0dfdbda3f56bf7d248ed87fcc383df114ecbb upstream.

UBSAN: Undefined behaviour in fs/btrfs/extent-tree.c:4623:21

signed integer overflow:
10808 * 262144 cannot be represented in type 'int [8]'

If 8192<=items<16384, we request a writeback of an insane number of pages which is benign (everything will be written). But if items>=16384, the space reservation won't be enough.

---
 fs/btrfs/extent-tree.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -4620,7 +4620,7 @@ static void shrink_delalloc(struct btrfs
 
 	/* Calc the number of the pages we need flush for space reservation */
 	items = calc_reclaim_items_nr(root, to_reclaim);
-	to_reclaim = items * EXTENT_SIZE_PER_ITEM;
+	to_reclaim = (u64)items * EXTENT_SIZE_PER_ITEM;
 
 	trans = (struct btrfs_trans_handle *)current->journal_info;
 	block_rsv = &root->fs_info->delalloc_block_rsv;

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/btrfs-fix-int32-overflow-in-shrink_delalloc.patch