Commit 7b3552d3 authored by Kumar Kartikeya Dwivedi's avatar Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov
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bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access 



It is not permitted to write to PTR_TO_MAP_KEY, but the current code in
check_helper_mem_access would allow for it, reject this case as well, as
helpers taking ARG_PTR_TO_UNINIT_MEM also take PTR_TO_MAP_KEY.

Fixes: 69c087ba ("bpf: Add bpf_for_each_map_elem() helper")
Signed-off-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220319080827.73251-4-memxor@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 97e6d7da

kernel/bpf/verifier.c

+5 −0
Original line number Diff line number Diff line
@@ -4861,6 +4861,11 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, 
		return check_packet_access(env, regno, reg->off, access_size,

					   zero_size_allowed);

	case PTR_TO_MAP_KEY:

		if (meta && meta->raw_mode) {

			verbose(env, "R%d cannot write into %s\n", regno,

				reg_type_str(env, reg->type));

			return -EACCES;

		}

		return check_mem_region_access(env, regno, reg->off, access_size,

					       reg->map_ptr->key_size, false);

	case PTR_TO_MAP_VALUE: