On Fri, Jul 28, 2017 at 11:05 PM, Daniel Borkmann <dan...@iogearbox.net> wrote:
> bpf_prog_size(prog->len) is not the correct length we want to dump
> back to user space. The code in bpf_prog_get_info_by_fd() uses this
> to copy prog->insnsi to user space, but bpf_prog_size(prog->len) also
> includes the size of struct bpf_prog itself plus program instructions
> and is usually used either in context of accounting or for bpf_prog_alloc()
> et al, thus we copy out of bounds in bpf_prog_get_info_by_fd()
> potentially. Use the correct bpf_prog_insn_size() instead.
Acked-by: Martin KaFai Lau <ka...@fb.com>
>
> Fixes: 1e2709769086 ("bpf: Add BPF_OBJ_GET_INFO_BY_FD")
> Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
> ---
> kernel/bpf/syscall.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 84bb399..6c772ad 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1312,7 +1312,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog
> *prog,
> }
>
> ulen = info.xlated_prog_len;
> - info.xlated_prog_len = bpf_prog_size(prog->len);
> + info.xlated_prog_len = bpf_prog_insn_size(prog);
> if (info.xlated_prog_len && ulen) {
> uinsns = u64_to_user_ptr(info.xlated_prog_insns);
> ulen = min_t(u32, info.xlated_prog_len, ulen);
> --
> 1.9.3
>
