From: Kumar Kartikeya Dwivedi memxor@gmail.com
commit 7b3552d3f9f6897851fc453b5131a967167e43c2 upstream.
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: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Signed-off-by: Kumar Kartikeya Dwivedi memxor@gmail.com Link: https://lore.kernel.org/r/20220319080827.73251-4-memxor@gmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/verifier.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4861,6 +4861,11 @@ static int check_helper_mem_access(struc 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: