Handle too-small buffers in Linux getlogin_r.

3 files changed, 18 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index a7fdafa..0d3d04a 100644
--- 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
index f508959..c0c74be 100644
--- 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
index d9c66fe..dad2671 100644
--- 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;
 }