Commit 8695a539 authored Oct 19, 2017 by John Fastabend Committed by David S. Miller Oct 22, 2017

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>

parent 43ebf97f

kernel/bpf/devmap.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

Admin message