[PATCH 5.4 126/151] btrfs: fix potential overflow in cluster_pages_for_defrag on 32bit arch

[Greg Kroah-Hartman]

From: Matthew Wilcox (Oracle) <wi...@infradead.org>

commit a1fbc6750e212c5675a4e48d7f51d44607eb8756 upstream.

On 32-bit systems, this shift will overflow for files larger than 4GB as
start_index is unsigned long while the calls to btrfs_delalloc_*_space
expect u64.

CC: sta...@vger.kernel.org # 4.4+
Fixes: df480633b891 ("btrfs: extent-tree: Switch to new delalloc space reserve 
and release")
Reviewed-by: Josef Bacik <jo...@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
Reviewed-by: David Sterba <dste...@suse.com>
[ define the variable instead of repeating the shift ]
Signed-off-by: David Sterba <dste...@suse.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>



---
 fs/btrfs/ioctl.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1255,6 +1255,7 @@ static int cluster_pages_for_defrag(stru
        u64 page_start;
        u64 page_end;
        u64 page_cnt;
+       u64 start = (u64)start_index << PAGE_SHIFT;
        int ret;
        int i;
        int i_done;
@@ -1271,8 +1272,7 @@ static int cluster_pages_for_defrag(stru
        page_cnt = min_t(u64, (u64)num_pages, (u64)file_end - start_index + 1);
 
        ret = btrfs_delalloc_reserve_space(inode, &data_reserved,
-                       start_index << PAGE_SHIFT,
-                       page_cnt << PAGE_SHIFT);
+                       start, page_cnt << PAGE_SHIFT);
        if (ret)
                return ret;
        i_done = 0;
@@ -1361,8 +1361,7 @@ again:
                btrfs_mod_outstanding_extents(BTRFS_I(inode), 1);
                spin_unlock(&BTRFS_I(inode)->lock);
                btrfs_delalloc_release_space(inode, data_reserved,
-                               start_index << PAGE_SHIFT,
-                               (page_cnt - i_done) << PAGE_SHIFT, true);
+                               start, (page_cnt - i_done) << PAGE_SHIFT, true);
        }
 
 
@@ -1389,8 +1388,7 @@ out:
                put_page(pages[i]);
        }
        btrfs_delalloc_release_space(inode, data_reserved,
-                       start_index << PAGE_SHIFT,
-                       page_cnt << PAGE_SHIFT, true);
+                       start, page_cnt << PAGE_SHIFT, true);
        btrfs_delalloc_release_extents(BTRFS_I(inode), page_cnt << PAGE_SHIFT);
        extent_changeset_free(data_reserved);
        return ret;