[PATCH net-next 2/2] sysctl: range checking in do_proc_dointvec_ms_jiffies_conv

[PATCH net-next 2/2] sysctl: range checking in do_proc_dointvec_ms_jiffies_conv

[Francesco Fusco]

When (integer) sysctl values are expressed in ms and have to be
represented internally as jiffies. The msecs_to_jiffies function
returns an unsigned long, which gets assigned to the integer.
This patch prevents the value to be assigned if bigger than
INT_MAX, done in a similar way as in cba9f3 ("Range checking in
do_proc_dointvec_(userhz_)jiffies_conv").

Signed-off-by: Francesco Fusco <ffusco@redhat.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: linux-kernel@vger.kernel.org
---
 kernel/sysctl.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ac09d98..00813e5 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2346,7 +2346,11 @@ static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp,
 					    int write, void *data)
 {
 	if (write) {
-		*valp = msecs_to_jiffies(*negp ? -*lvalp : *lvalp);
+		unsigned long jif = 0;
+		jif =  msecs_to_jiffies(*negp ? -*lvalp : *lvalp);
+		if (jif > INT_MAX)
+			return 1;
+		*valp = (int)jif;
 	} else {
 		int val = *valp;
 		unsigned long lval;
-- 
1.8.3.1

Re: [PATCH net-next 2/2] sysctl: range checking in do_proc_dointvec_ms_jiffies_conv

[Sergei Shtylyov]

Hello.

On 24-07-2013 12:39, Francesco Fusco wrote:

> When (integer) sysctl values are expressed in ms and have to be
> represented internally as jiffies. The msecs_to_jiffies function
> returns an unsigned long, which gets assigned to the integer.
> This patch prevents the value to be assigned if bigger than
> INT_MAX, done in a similar way as in cba9f3 ("Range checking in
> do_proc_dointvec_(userhz_)jiffies_conv").

> Signed-off-by: Francesco Fusco <ffusco@redhat.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: linux-kernel@vger.kernel.org
> ---
>   kernel/sysctl.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)

> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index ac09d98..00813e5 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2346,7 +2346,11 @@ static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp,
>   					    int write, void *data)
>   {
>   	if (write) {
> -		*valp = msecs_to_jiffies(*negp ? -*lvalp : *lvalp);
> +		unsigned long jif = 0;

    Pointless initializer. And an empty line wouldn't hurt after declaration.

> +		jif =  msecs_to_jiffies(*negp ? -*lvalp : *lvalp);

    One space after = is enough.

> +		if (jif > INT_MAX)
> +			return 1;
> +		*valp = (int)jif;

WBR, Sergei

Re: [PATCH net-next 2/2] sysctl: range checking in do_proc_dointvec_ms_jiffies_conv

[David Miller]

From: Francesco Fusco <ffusco@redhat.com>
Date: Wed, 24 Jul 2013 10:39:07 +0200

> When (integer) sysctl values are expressed in ms and have to be
> represented internally as jiffies. The msecs_to_jiffies function
> returns an unsigned long, which gets assigned to the integer.
> This patch prevents the value to be assigned if bigger than
> INT_MAX, done in a similar way as in cba9f3 ("Range checking in
> do_proc_dointvec_(userhz_)jiffies_conv").
> 
> Signed-off-by: Francesco Fusco <ffusco@redhat.com>

Applied with the changes suggested by Sergei.