1 files changed, 6 insertions, 1 deletions
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 10a057062..afa1fd439 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -576,12 +576,17 @@ Path resolveExprPath(Path path)
 {
     assert(path[0] == '/');
 
+    unsigned int followCount = 0, maxFollow = 1024;
+
     /* If `path' is a symlink, follow it.  This is so that relative
        path references work. */
     struct stat st;
     while (true) {
+        // Basic cycle/depth limit to avoid infinite loops.
+        if (++followCount >= maxFollow)
+            throw Error("too many symbolic links encountered while traversing the path '%s'", path);
         if (lstat(path.c_str(), &st))
-            throw SysError(format("getting status of '%1%'") % path);
+            throw SysError("getting status of '%s'", path);
         if (!S_ISLNK(st.st_mode)) break;
         path = absPath(readLink(path), dirOf(path));
     }