Description of problem:

bash uses a partial uninitialized structure passed to the sendmsg syscall.

Version-Release number of selected component (if applicable):

bash-4.2.37-3.fc18.x86_64

How reproducible:

Always

Steps to Reproduce:
1. run valgrind -q bash
2. exit
  
Actual results:

==3332== Syscall param socketcall.sendmsg(msg.msg_name) points to uninitialised byte(s)
==3332==    at 0x5563200: __sendmsg_nocancel (syscall-template.S:82)
==3332==    by 0x489A77: readline (readline.c:346)
==3332==    by 0x41E5AB: yy_readline_get (parse.y:1443)
==3332==    by 0x4204F8: shell_getc (parse.y:1376)
==3332==    by 0x422E95: read_token.constprop.8 (parse.y:2908)
==3332==    by 0x4258BF: yyparse (parse.y:2517)
==3332==    by 0x41DE69: parse_command (eval.c:229)
==3332==    by 0x41DF35: read_command (eval.c:273)
==3332==    by 0x41E182: reader_loop (eval.c:138)
==3332==    by 0x41C8EE: main (shell.c:759)
==3332==  Address 0x7feffece2 is on thread 1's stack
==3332== 

Expected results:

No output from valgrind.

Additional info:

Valgrind is right that there is uninitialized data used in the sendmsg syscall. When using nl_family = AF_NETLINK the nl_pad field should be initialized to zero and it isn't. This is unlikely to cause real problems in practice since this field is currently unused. But in the unlikely event that field does get used in the future it could be an issue that it isn't explicitly set to zero. Also it makes valgrind happy :)

It looks like the audit.patch is fedora local and not upstream. If it is already upstream please do let me know and I'll post patch there.

Patch (against the audit patch) is simple:

index 8de4980..f0e0ec4 100644
--- a/bash-3.2-audit.patch
+++ b/bash-3.2-audit.patch
@@ -44,7 +44,7 @@ diff -up bash-4.0/lib/readline/readline.c.audit bash-4.0/lib/r
  /* System-specific feature definitions and include files. */
  #include "rldefs.h"
  #include "rlmbutil.h"
-@@ -297,7 +303,47 @@ rl_set_prompt (prompt)
+@@ -297,7 +303,48 @@ rl_set_prompt (prompt)
    rl_visible_prompt_length = rl_expand_prompt (rl_prompt);
    return 0;
  }
@@ -76,6 +76,7 @@ diff -up bash-4.0/lib/readline/readline.c.audit bash-4.0/lib/r
 +  iov[1].iov_base = string;
 +  iov[1].iov_len = size;
 +  addr.nl_family = AF_NETLINK;
++  addr.nl_pad = 0;
 +  addr.nl_pid = 0;
 +  addr.nl_groups = 0;
 +  msg.msg_name = &addr;