Re: [PATCH] sysctl: fix min/max handling in __do_proc_doulongvec_minmax()

["Américo Wang" <xiyou.wangcong@gmail.com>]

On Sat, Oct 02, 2010 at 03:17:49PM +0200, Eric Dumazet wrote:
>When proc_doulongvec_minmax() is used with an array of longs,
>and no min/max check requested (.extra1 or .extra2 being NULL), we
>dereference a NULL pointer for the second element of the array.
>
>Noticed while doing some changes in network stack for the "16TB problem"
>
>Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
>---
> kernel/sysctl.c |    3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>index f88552c..4fba86d 100644
>--- a/kernel/sysctl.c
>+++ b/kernel/sysctl.c
>@@ -2500,7 +2500,8 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
> 				break;
> 			if (neg)
> 				continue;
>-			if ((min && val < *min) || (max && val > *max))
>+			if ((table->extra1 && val < *min) ||
>+			    (table->extra2 && val > *max))
> 				continue;


Yes? This is wrong for me, min and max are pointers to ->extra{1,2},
they are increased within the for loop, you are only checking the
the pointer to the first element of ->extra{1,2}.