[PATCH] sysctl: fix min/max handling in__do_proc_doulongvec_minmax()

[Eric Dumazet]

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@xxxxxxxxx>
---
 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;
 			*i = val;
 		} else {


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