Second call of sysctl() is used to gather a proper size of a memory chunk

needed to hold the GEOM tree. At this point, pointer 'p' has an improper
value (as it was used previously), and we're getting EFAULT. Fix this
functionality by passing NULL instead of 'p'.

This fixes mdconfig(8) -l output with high number of md(4) devices.

   Found by:	kris
Reviewed by:	phk

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/libgeom/geom_getxml.c b/lib/libgeom/geom_getxml.c
index fbc9cb8..68ff91b 100644
--- a/lib/libgeom/geom_getxml.c
+++ b/lib/libgeom/geom_getxml.c
@@ -53,7 +53,7 @@ geom_getxml()
 		free(p);
 	}
 	l = 0;
-	i = sysctlbyname("kern.geom.confxml", p, &l, NULL, 0);
+	i = sysctlbyname("kern.geom.confxml", NULL, &l, NULL, 0);
 	if (i != 0)
 		return (NULL);
 	p = malloc(l + 4096);