r14869@catbus: nickm | 2007-08-31 08:49:26 -0400

 Fix a segfault in expand_filename("~").  Found by lindi.


svn:r11332

ChangeLog

@@ -19,6 +19,8 @@ Changes in version 0.2.0.7-alpha - 2007-??-??
       bug 467.
     - On OSX, stop warning the user that kqueue support in libevent is
       "experimental", since it seems to have worked fine for ages.
+    - Fix a user-triggerable segfault in expand_filename().  (There isn't
+      a way to trigger this remotely.)
 
   o Code simplifications and refactoring:
     - Revamp file-writing logic so we don't need to have the entire contents

src/common/util.c

@@ -1839,7 +1839,7 @@ expand_filename(const char *filename)
         return NULL;
       }
       home = tor_strdup(home);
-      rest = strlen(filename)>=2?(filename+2):NULL;
+      rest = strlen(filename)>=2?(filename+2):"";
     } else {
 #ifdef HAVE_PWD_H
       char *username, *slash;
@@ -1854,7 +1854,7 @@ expand_filename(const char *filename)
         return NULL;
       }
       tor_free(username);
-      rest = slash ? (slash+1) : NULL;
+      rest = slash ? (slash+1) : "";
 #else
       log_warn(LD_CONFIG, "Couldn't expend homedir on system without pwd.h");
       return tor_strdup(filename);
@@ -1869,7 +1869,7 @@ expand_filename(const char *filename)
      * Round up to 16 in case we can't do math. */
     len = strlen(home)+strlen(rest)+16;
     result = tor_malloc(len);
-    tor_snprintf(result,len,"%s"PATH_SEPARATOR"%s",home,rest?rest:"");
+    tor_snprintf(result,len,"%s"PATH_SEPARATOR"%s",home,rest);
     tor_free(home);
     return result;
   } else {