UBIFS: fix use of freed ubifs_orphan objects

The last orphan in the cnext list has its cnext set to NULL. Because
of that, ubifs_delete_orphan assumes that it is not on the cnext list
and frees it immediately instead of adding it to the dnext list. The
freed orphan is later modified by write_orph_node.

This can cause various inconsistencies including directory entries
that cannot be removed and this error:

UBIFS error (pid 20685): layout_cnodes: LPT out of space at LEB 14:129009 needing 17, done_ltab 1, done_lsave 1

This is a regression introduced by
"7074e5eb UBIFS: remove invalid reference to list iterator variable".

This change adds an explicit flag to ubifs_orphan indicating whether
it is pending commit.

Signed-off-by: Adam Thomas <adamthomas1111@gmail.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v3.6+
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

2 files changed, 9 insertions, 2 deletions

diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
index 769701ccb5c9..8534d9c6492f 100644
--- a/fs/ubifs/orphan.c
+++ b/fs/ubifs/orphan.c
@@ -132,7 +132,7 @@ void ubifs_delete_orphan(struct ubifs_info *c, ino_t inum)
                                         (unsigned long)inum);
                                 return;
                         }
-                        if (o->cnext) {
+                        if (o->cmt) {
                                 o->dnext = c->orph_dnext;
                                 c->orph_dnext = o;
                                 spin_unlock(&c->orphan_lock);
@@ -172,7 +172,9 @@ int ubifs_orphan_start_commit(struct ubifs_info *c)
         last = &c->orph_cnext;
         list_for_each_entry(orphan, &c->orph_new, new_list) {
                 ubifs_assert(orphan->new);
+                ubifs_assert(!orphan->cmt);
                 orphan->new = 0;
+                orphan->cmt = 1;
                 *last = orphan;
                 last = &orphan->cnext;
         }
@@ -299,7 +301,9 @@ static int write_orph_node(struct ubifs_info *c, int atomic)
         cnext = c->orph_cnext;
         for (i = 0; i < cnt; i++) {
                 orphan = cnext;
+                ubifs_assert(orphan->cmt);
                 orph->inos[i] = cpu_to_le64(orphan->inum);
+                orphan->cmt = 0;
                 cnext = orphan->cnext;
                 orphan->cnext = NULL;
         }
@@ -378,6 +382,7 @@ static int consolidate(struct ubifs_info *c)
                 list_for_each_entry(orphan, &c->orph_list, list) {
                         if (orphan->new)
                                 continue;
+                        orphan->cmt = 1;
                         *last = orphan;
                         last = &orphan->cnext;
                         cnt += 1;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index d133c276fe05..c16fff7271d3 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -904,6 +904,7 @@ struct ubifs_budget_req {
  * @dnext: next orphan to delete
  * @inum: inode number
  * @new: %1 => added since the last commit, otherwise %0
+ * @cmt: %1 => commit pending, otherwise %0
  */
 struct ubifs_orphan {
         struct rb_node rb;
@@ -912,7 +913,8 @@ struct ubifs_orphan {
         struct ubifs_orphan *cnext;
         struct ubifs_orphan *dnext;
         ino_t inum;
-        int new;
+        unsigned new:1;
+        unsigned cmt:1;
 };
 
 /**