NTFS: Fix handling of valid but empty mapping pairs array in

      fs/ntfs/runlist.c::ntfs_mapping_pairs_decompress().

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

2 files changed, 5 insertions, 0 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index f4c27f7c1b6a..8fe38c801166 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -46,6 +46,8 @@ ToDo/Notes:
         - Fix two nasty runlist merging bugs that had gone unnoticed so far.
           Thanks to Stefano Picerno for the bug report.
         - Remove two bogus BUG_ON()s from fs/ntfs/mft.c.
+        - Fix handling of valid but empty mapping pairs array in
+          fs/ntfs/runlist.c::ntfs_mapping_pairs_decompress().
 
 2.1.23 - Implement extension of resident files and make writing safe as well as
          many bug fixes, cleanups, and enhancements...
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c
index d26a1be530c5..e4c4716939de 100644
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -760,6 +760,9 @@ runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
                 ntfs_error(vol->sb, "Corrupt attribute.");
                 return ERR_PTR(-EIO);
         }
+        /* If the mapping pairs array is valid but empty, nothing to do. */
+        if (!vcn && !*buf)
+                return old_rl;
         /* Current position in runlist array. */
         rlpos = 0;
         /* Allocate first page and set current runlist size to one page. */