Handle too-small buffers in Linux getlogin_r.

git-mirror · May 5, 2010 · 5ae958d · 5ae958d
1 parent 3155f06
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diff --git a/ChangeLog b/ChangeLog
@@ -1,5 +1,9 @@
 2010-05-05  Ulrich Drepper  <drepper@redhat.com>
 
+	[BZ #11571]
+	* sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): Handle
+	too small buffers according to the standard.
+
 	* sysdeps/unix/sysv/linux/kernel-features.h: Alpha doesn't have to be
 	handled here anymore.
 	Patch mostly by Matt Turner <mattst88@gmail.com>.

diff --git a/NEWS b/NEWS
@@ -16,7 +16,7 @@ Version 2.12
   11185, 11186, 11187, 11188, 11189, 11190, 11191, 11192, 11193, 11194,
   11200, 11230, 11235, 11242, 11254, 11258, 11271, 11272, 11276, 11279,
   11287, 11292, 11319, 11332, 11333, 11387, 11389, 11390, 11394, 11397,
-  11410, 11438, 11449, 11470, 11471, 11520, 11537, 11538
+  11410, 11438, 11449, 11470, 11471, 11520, 11537, 11538, 11571
 
 * New interfaces: pthread_getname_np, pthread_setname_np
 

diff --git a/sysdeps/unix/sysv/linux/getlogin_r.c b/sysdeps/unix/sysv/linux/getlogin_r.c
@@ -81,13 +81,22 @@ __getlogin_r_loginuid (name, namesize)
   if (tpwd == NULL)
     goto fail;
 
-  strncpy (name, pwd.pw_name, namesize - 1);
-  name[namesize - 1] = '\0';
-
+  int result = 0;
+  size_t needed = strlen (pwd.pw_name) + 1;
+  if (needed > namesize)
+    {
+      __set_errno (ERANGE);
+      result = ERANGE;
+      goto out;
+    }
+
+  memcpy (name, pwd.pw_name, needed);
+
+ out:
   if (use_malloc)
     free (buf);
 
-  return 0;
+  return result;
 }