linux-kernel - Re: [BUG] timer_migration interface accepts any number as input in 2.6.30-git9

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Date:	Wed, 17 Jun 2009 18:41:48 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	Arun R Bharadwaj <arun@...ux.vnet.ibm.com>
Cc:	poornima nayak <mpnayak@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG] timer_migration interface accepts any number as input in
	2.6.30-git9

On Wed, Jun 17, 2009 at 03:51:26PM +0530, Arun R Bharadwaj wrote:
>* poornima nayak <mpnayak@...ux.vnet.ibm.com> [2009-06-17 14:42:16]:
>
>> Hi
>> 
>> Timer migration interface /proc/sys/kernel/timer_migration in
>> 2.6.30-git9 accepts any numerical value as input.
>> Steps to reproduce 
>> 1. echo -6666666 > /proc/sys/kernel/timer_migration
>> 2. cat /proc/sys/kernel/timer_migration
>> -6666666
>> 
>> 1. echo 44444444444444444444444444444444444444444444444444444444444 > /proc/sys/kernel/timer_migration
>> 2. cat /proc/sys/kernel/timer_migration
>> -1357789412
>> 
>> Expected behavior: Should 'echo: write error: Invalid argument' while
>> setting any value other then 0 & 1
>> 
>> Regards
>> Poornima
>> 
>
>Hi Poornima,
>
>Thanks for reporting the bug.
>Hope this patch removes the bug.
>The patch is based against the latest -tip/master.
>
>--arun
>
>
>Signed-off-by: Arun R Bharadwaj <arun@...ux.vnet.ibm.com>

Reviewed-by: WANG Cong <xiyou.wangcong@...il.com>


My fix goes further, the further part of it is shown below. :)
Mind to have a look?

Not tested yet.

Signed-off-by: WANG Cong <xiyou.wangcong@...il.com>

-----
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ab462b9..bc27e00 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2331,7 +2331,8 @@ static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
 			if (*p < '0' || *p > '9')
 				break;
 
-			lval = simple_strtoul(p, &p, 0);
+			if (strict_strtoul(p, 0, &lval))
+				return -EINVAL;
 
 			len = p-buf;
 			if ((len < left) && *p && !isspace(*p))
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 756ccaf..ff2ca5c 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -163,11 +163,14 @@ int strict_strtoul(const char *cp, unsigned int base, unsigned long *res)
 	char *tail;
 	unsigned long val;
 	size_t len;
+	char tmp[32];
 
 	*res = 0;
 	len = strlen(cp);
 	if (len == 0)
 		return -EINVAL;
+	if (len > snprintf(tmp, "%ld", ULONG_MAX))
+		return -EINVAL;
 
 	val = simple_strtoul(cp, &tail, base);
 	if (tail == cp)
--
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