Re: [PATCH] Kernel parameter parsing fix

[Zhu, Yi]

On Fri, 21 May 2004, Andrew Morton wrote:
> 
> Can you explain waht problem this solves?  An example?

The real problem happens on 2.6.5 -mm kernel, but not vanilla kernel
because of the early_param patch.

For example in arch/i386/kernel/setup.c:
__early_param("acpi", early_acpi);

In drivers/acpi/osl.c:
__setup("acpi_os_name=", acpi_os_name_setup);

So if one passes kernel parameter in the bootloader as below,

"acpi=force acpi_os_name=my_override_name"

the "acpi_os_name=" parameter will take the setup func for "acpi",
because they begin with the same string "acpi".


Vanilla kernel doesn't have the problem now because most of the
parameter strings have a trailing '=', so "acpi_os_name" won't
take the setup func for "acpi=". But a safer way is to checkup 
the parameter string when parsing it as the patch did.

> 
> The patch is wordwrapped
Sorry, please try this time.

--- linux-2.6.6.orig/init/main.c	2004-05-14 13:38:31.000000000 +0800
+++ linux-2.6.6/init/main.c	2004-05-15 00:25:41.339261792 +0800
@@ -149,11 +149,15 @@ static int __init obsolete_checksetup(ch
 {
 	struct obs_kernel_param *p;
 	extern struct obs_kernel_param __setup_start, __setup_end;
+	char *ptr;
+	int len = strlen(line);
 
+	if ((ptr = strchr(line, '=')))
+		len = ptr - line;
 	p = &__setup_start;
 	do {
 		int n = strlen(p->str);
-		if (!strncmp(line, p->str, n)) {
+		if (len <= n && !strncmp(line, p->str, n)) {
 			if (!p->setup_func) {
 				printk(KERN_WARNING "Parameter %s is
obsolete, ignored\n", p->str);
 				return 1;


Thanks,
-- 
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Intel Corp.

Zhu Yi (Chuyee)

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