From 8695a5395661fbb4a4f26c97f801f3800ae4754e Mon Sep 17 00:00:00 2001
From: John Fastabend <john.r.fastabend@gmail.com>
Date: Thu, 19 Oct 2017 09:03:52 -0700
Subject: bpf: devmap fix arithmetic overflow in bitmap_size calculation

An integer overflow is possible in dev_map_bitmap_size() when
calculating the BITS_TO_LONG logic which becomes, after macro
replacement,

	(((n) + (d) - 1)/ (d))

where 'n' is a __u32 and 'd' is (8 * sizeof(long)). To avoid
overflow cast to u64 before arithmetic.

Reported-by: Richard Weinberger <richard@nod.at>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 kernel/bpf/devmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'kernel')

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 52e0548ba548..e745d6a88224 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -69,7 +69,7 @@ static LIST_HEAD(dev_map_list);
 
 static u64 dev_map_bitmap_size(const union bpf_attr *attr)
 {
-	return BITS_TO_LONGS(attr->max_entries) * sizeof(unsigned long);
+	return BITS_TO_LONGS((u64) attr->max_entries) * sizeof(unsigned long);
 }
 
 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
-- 
cgit