From 3889db173b4a44659a780459892c716c8158036d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Grubbstr=C3=B6m=20=28Grubba=29?=
<grubba@grubba.org>
Date: Fri, 17 Apr 1998 00:56:52 +0200
Subject: [PATCH] f_get_groups_for_user() might now be deadlock free.
Rev: src/modules/system/passwords.c:1.11
---
src/modules/system/passwords.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/src/modules/system/passwords.c b/src/modules/system/passwords.c
index 18be06a52f..a3badffd58 100644
--- a/src/modules/system/passwords.c
+++ b/src/modules/system/passwords.c
@@ -1,5 +1,5 @@
/*
- * $Id: passwords.c,v 1.10 1998/04/16 22:44:22 grubba Exp $
+ * $Id: passwords.c,v 1.11 1998/04/16 22:56:52 grubba Exp $
*
* Password handling for Pike.
*
@@ -9,6 +9,9 @@
* safe. If some other function executes a *pw* function
* without locking the password_protection_mutex, we are
* pretty much screwed.
+ *
+ * NOTE: To avoid deadlocks, any locking of password_protection_mutex
+ * MUST be done within THREADS_ALLOW()/THREADS_DISALLOW().
*/
/*
@@ -19,7 +22,7 @@
#include "global.h"
-RCSID("$Id: passwords.c,v 1.10 1998/04/16 22:44:22 grubba Exp $");
+RCSID("$Id: passwords.c,v 1.11 1998/04/16 22:56:52 grubba Exp $");
#include "module_support.h"
#include "interpret.h"
@@ -518,22 +521,27 @@ void f_get_groups_for_user(INT32 arg)
check_all_args("get_groups_for_user",arg,BIT_INT | BIT_STRING, 0);
pop_n_elems(arg-1);
a=low_allocate_array(0,10);
- mt_lock(&password_protection_mutex);
if(sp[-1].type == T_INT)
{
int uid=sp[-1].u.integer;
THREADS_ALLOW();
+ mt_lock(&password_protection_mutex);
pw=getpwuid(uid);
THREADS_DISALLOW();
+
sp[-1].u.string=make_shared_string(pw->pw_name);
sp[-1].type=T_STRING;
user=sp[-1].u.string->str;
}else{
user=sp[-1].u.string->str;
THREADS_ALLOW();
+ mt_lock(&password_protection_mutex);
pw=getpwnam(user);
THREADS_DISALLOW();
}
+
+ /* NOTE: password_protection_mutex is still locked here. */
+
if(!pw)
{
mt_unlock(&password_protection_mutex);
@@ -562,7 +570,7 @@ void f_get_groups_for_user(INT32 arg)
if(gr->gr_mem[e]) break;
}
- THREADS_DISALLOW();
+ THREADS_DISALLOW(); /* Is there a risk of deadlock here? */
if(!gr) break;
push_int(gr->gr_gid);
--
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