preproc.c: Fix NULL deref on token pasting

In case if there is a whitespace before
'paste' token we may reach NULL dereference
in strlen since paste_head will point to
TOK_WHITESPACE. Fix it.

[mainstream adabc1576b957fc7d929d2c7e749b4f45f7293aa]

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/preproc.c b/preproc.c
index 1af58d92..3c358284 100644
--- a/preproc.c
+++ b/preproc.c
@@ -3594,7 +3594,9 @@ static bool paste_tokens(Token **head, bool handle_paste_tokens)
             }
             /* else fall through */
         default:
-            tail = paste_head = &t->next;
+            tail = &t->next;
+            if (!tok_type_(t->next, TOK_WHITESPACE))
+                paste_head = tail;
             break;
         }
     }