[PATCH v2] fts: avoid crash when a cycle is added while traversing

[Kamil Dudka]

This could be triggered by auto-mounting a recursive bind mount.
Reported by Michael Chapman in: https://bugzilla.redhat.com/1188498
* lib/fts.c (fts_read): Avoid removing the original hash table item
when leaving a directory that caused a cycle, and preserve the FTS_DC
flag.
---
 ChangeLog |  9 +++++++++
 lib/fts.c | 13 ++++++++++---
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c4cb47f..9daa33c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2015-02-11  Kamil Dudka  <address@hidden>
+
+       fts: avoid crash when a cycle is added while traversing
+       This could be triggered by auto-mounting a recursive bind mount.
+       Reported by Michael Chapman in: https://bugzilla.redhat.com/1188498
+       * lib/fts.c (fts_read): Avoid removing the original hash table item
+       when leaving a directory that caused a cycle, and preserve the FTS_DC
+       flag.
+
 2015-02-11  Pádraig Brady  <address@hidden>
 
        tests: avoid recent -Werror=unused-variable regression in test-locale
diff --git a/lib/fts.c b/lib/fts.c
index 5cb4cb0..a5b1741 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -1091,9 +1091,16 @@ cd_dot_dot:
                 p->fts_errno = errno;
                 SET(FTS_STOP);
         }
-        p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
-        if (p->fts_errno == 0)
-                LEAVE_DIR (sp, p, "3");
+
+        /* If the directory causes a cycle, preserve the FTS_DC flag and keep
+         * the corresponding dev/ino pair in the hash table.  It is going to be
+         * removed when leaving the original directory.
+         */
+        if (p->fts_info != FTS_DC) {
+            p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
+            if (p->fts_errno == 0)
+                    LEAVE_DIR (sp, p, "3");
+        }
         return ISSET(FTS_STOP) ? NULL : p;
 }
 
-- 
2.1.0