FYI: HEAD: fix slist_remove: return 1st match, NULL deref

[Ralf Wildenhues]

Hello Libtool patches,

while fixing another issue in libltdl (other mail coming up), I noted
this glitch in slist.c: Inside the for loop in slist_remove, if we
find the item inside the loop to be head->next, head advances by two
->next derefs, and so may be NULL if the matched item was the last one
in the list, so the subsequent loop criterion
  head->next != NULL

causes a NULL dereference.  Breaking out of the loop in case we found
our result fixes this, and also causes slist_remove to actually return
the first matching item always.  This bug is currently not exposed in
libltdl, because our only use of slist_remove is still ineffective ATM
(which is, in effect, the other pending bug).

Cheers,
Ralf

2007-08-29  Ralf Wildenhues  <address@hidden>

        * libltdl/slist.c (slist_remove): When a matching item is found,
        break out of the loop to return the first match; also fixes
        possible NULL dereference.

Index: libltdl/slist.c
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/slist.c,v
retrieving revision 1.8
diff -u -r1.8 slist.c
--- libltdl/slist.c     25 Mar 2007 12:12:42 -0000      1.8
+++ libltdl/slist.c     29 Aug 2007 20:58:42 -0000
@@ -1,6 +1,6 @@
 /* slist.c -- generalised singly linked lists
 
-   Copyright (C) 2000, 2004 Free Software Foundation, Inc.
+   Copyright (C) 2000, 2004, 2007 Free Software Foundation, Inc.
    Written by Gary V. Vaughan, 2000
 
    NOTE: The canonical source of this file is maintained with the
@@ -101,6 +101,7 @@
            {
              stale             = head->next;
              head->next        = stale->next;
+             break;
            }
        }
     }