NTFS: Fix two nasty runlist merging bugs that had gone unnoticed so far.

      Thanks to Stefano Picerno for the bug report.

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

2 files changed, 5 insertions, 2 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index c5bbedff5ae5..4bc8f91c5fc0 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -43,6 +43,8 @@ ToDo/Notes:
         - Use ntfs_malloc_nofs_nofail() in the two critical regions in
           fs/ntfs/runlist.c::ntfs_runlists_merge().  This means we no longer
           need to panic() if the allocation fails as it now cannot fail.
+        - Fix two nasty runlist merging bugs that had gone unnoticed so far.
+          Thanks to Stefano Picerno for the bug report.
 
 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 3bb4a57d1fa9..d26a1be530c5 100644
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -542,6 +542,7 @@ runlist_element *ntfs_runlists_merge(runlist_element *drl,
                         /* Scan to the end of the source runlist. */
                         for (dend = 0; likely(drl[dend].length); dend++)
                                 ;
+                        dend++;
                         drl = ntfs_rl_realloc(drl, dend, dend + 1);
                         if (IS_ERR(drl))
                                 return drl;
@@ -611,8 +612,8 @@ runlist_element *ntfs_runlists_merge(runlist_element *drl,
                  ((drl[dins].vcn + drl[dins].length) <=      /* End of hole   */
                   (srl[send - 1].vcn + srl[send - 1].length)));
 
-        /* Or we'll lose an end marker */
-        if (start && finish && (drl[dins].length == 0))
+        /* Or we will lose an end marker. */
+        if (finish && !drl[dins].length)
                 ss++;
         if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
                 finish = FALSE;