lib/port.c: getportent(): Make sure there are at least 2 ':' in the line

Otherwise, the line is invalidly formatted, and we ignore it.

For fixing cherry-pick conflicts, this also includes (minimal) changes
from:

-  59e5eef38f89 ("contrib, lib/, src/, tests/: Use stpcpy(3) instead of its pattern")
   <https://github.com/shadow-maint/shadow/pull/1035>

Closes: <https://github.com/shadow-maint/shadow/issues/1036>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Cherry-picked-from: c3f97e251ef1 ("lib/port.c: getportent(): Make sure there are at least 2 ':' in the line")
Link: <https://github.com/shadow-maint/shadow/pull/1037>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

diff --git a/lib/port.c b/lib/port.c
index bda194446b399bea53e2fa669632ceb6be2b6293..6f05493263a5c17ebe02bd8acafd7be5d4bcfdd4 100644 (file)
--- a/lib/port.c
+++ b/lib/port.c
@@ -144,23 +144,19 @@ next:
         * TTY devices.
         */
 
+       if (strchr(buf, ':') == NULL)
+               goto next;
+
        port.pt_names = ttys;
        for (cp = buf, j = 0; j < PORT_TTY; j++) {
                port.pt_names[j] = cp;
                cp = strpbrk(cp, ":,");
-               if (cp == NULL)
-                       goto next;      /* line format error */
-
-               if (':' == *cp) {       /* end of tty name list */
+               if (':' == *cp)         /* end of tty name list */
                        break;
-               }
-
-               if (',' == *cp) {       /* end of current tty name */
-                       *cp++ = '\0';
-               }
+               if (',' == *cp)         /* end of current tty name */
+                       stpcpy(cp++, "");
        }
-       *cp = '\0';
-       cp++;
+       stpcpy(cp++, "");
        port.pt_names[j] = NULL;
 
        /*
@@ -170,6 +166,9 @@ next:
         * The last entry in the list is a NULL pointer.
         */
 
+       if (strchr(cp, ':') == NULL)
+               goto next;
+
        if (':' != *cp) {
                port.pt_users = users;
                port.pt_users[0] = cp;