[nasm:nasm-2.13.xx] preproc: Fix SIGSEGV if not data provided for implicit pasting

[nasm-bot f. C. G. <gor...@gm...>]

Commit-ID:  6f8109ebf18e3de69a8a2ad63867fe8498e49bf0
Gitweb:     http://repo.or.cz/w/nasm.git?a=commitdiff;h=6f8109ebf18e3de69a8a2ad63867fe8498e49bf0
Author:     Cyrill Gorcunov <gor...@gm...>
AuthorDate: Sun, 22 Oct 2017 21:26:36 +0300
Committer:  Cyrill Gorcunov <gor...@gm...>
CommitDate: Sun, 22 Oct 2017 21:26:36 +0300

preproc: Fix SIGSEGV if not data provided for implicit pasting

https://bugzilla.nasm.us/show_bug.cgi?id=3392423

Signed-off-by: Cyrill Gorcunov <gor...@gm...>


---
 asm/preproc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/asm/preproc.c b/asm/preproc.c
index 43b62aa..9642edc 100644
--- a/asm/preproc.c
+++ b/asm/preproc.c
@@ -3848,8 +3848,8 @@ static bool paste_tokens(Token **head, const struct tokseq_match *m,
                     next = next->next;
                 }
 
-                /* No match */
-                if (tok == next)
+                /* No match or no text to process */
+                if (tok == next || len == 0)
                     break;
 
                 len += strlen(tok->text);