linux-kernel - Re: [PATCH 3/3] init/Kconfig: Add option to set modprobe command

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Date:	Fri, 10 May 2013 15:12:47 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Lucas De Marchi <lucas.de.marchi@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 3/3] init/Kconfig: Add option to set modprobe command

On 05/10, Oleg Nesterov wrote:
>
> On 05/10, Lucas De Marchi wrote:
> >
> > -char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe -q --";
> > +char modprobe_path[KMOD_PATH_LEN] = CONFIG_DEFAULT_MODULE_LOAD_BIN;
>
> But even after 1/3 and 2/3 this can break free_modprobe_argv() ?
> It assumes that argv[3] is module_name.

I'd suggest the patch below instead of 1 + 2. We can simply change
call_modprobe() to use kasprintf() + argv_split().

Oleg.

 kmod.c |   38 ++++++++++++++++----------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

--- x/kernel/kmod.c
+++ x/kernel/kmod.c
@@ -64,20 +64,16 @@ static DECLARE_RWSEM(umhelper_sem);
 
 #ifdef CONFIG_MODULES
 
-/*
-	modprobe_path is set via /proc/sys.
-*/
-char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
+/* modprobe_path is set via /proc/sys/kernel/modprobe */
+char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe -q --";
 
 static void free_modprobe_argv(struct subprocess_info *info)
 {
-	kfree(info->argv[3]); /* check call_modprobe() */
-	kfree(info->argv);
+	argv_free(info->argv);
 }
 
 static int call_modprobe(char *module_name, int wait)
 {
-	struct subprocess_info *info;
 	static char *envp[] = {
 		"HOME=/",
 		"TERM=linux",
@@ -85,31 +81,29 @@ static int call_modprobe(char *module_na
 		NULL
 	};
 
-	char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
-	if (!argv)
-		goto out;
+	struct subprocess_info *info;
+	char **argv;
+	char *args;
 
-	module_name = kstrdup(module_name, GFP_KERNEL);
-	if (!module_name)
-		goto free_argv;
+	args = kasprintf(GFP_KERNEL, "%s %s", modprobe_path, module_name);
+	if (!args)
+		goto out;
 
-	argv[0] = modprobe_path;
-	argv[1] = "-q";
-	argv[2] = "--";
-	argv[3] = module_name;	/* check free_modprobe_argv() */
-	argv[4] = NULL;
+	argv = argv_split(GFP_KERNEL, args, NULL);
+	if (!argv)
+		goto free_args;
 
 	info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
 					 NULL, free_modprobe_argv, NULL);
 	if (!info)
-		goto free_module_name;
+		goto free_argv;
 
 	return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
 
-free_module_name:
-	kfree(module_name);
 free_argv:
-	kfree(argv);
+	argv_free(argv);
+free_args:
+	kfree(args);
 out:
 	return -ENOMEM;
 }

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