On Wed, Nov 15, 2023 at 9:18 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> A test case to verify that imprecise scalars widening is applied to
> callback bodies on repetative iteration.
typo: repetitive? repeating? successive? subsequent?
>
> Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
> ---
> .../bpf/progs/verifier_iterating_callbacks.c | 20 +++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
> index fa9429f77a81..598c1e984b26 100644
> --- a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
> +++ b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
> @@ -25,6 +25,7 @@ struct buf_context {
>
> struct num_context {
> __u64 i;
> + __u64 j;
> };
>
> __u8 choice_arr[2] = { 0, 1 };
> @@ -69,6 +70,25 @@ int unsafe_on_zero_iter(void *unused)
> return choice_arr[loop_ctx.i];
> }
>
> +static int widening_cb(__u32 idx, struct num_context *ctx)
> +{
> + ++ctx->i;
> + return 0;
> +}
> +
> +SEC("?raw_tp")
> +__success
> +int widening(void *unused)
> +{
> + struct num_context loop_ctx = { .i = 0, .j = 1 };
> +
> + bpf_loop(100, widening_cb, &loop_ctx, 0);
> + /* loop_ctx.j is not changed during callback iteration,
> + * verifier should not apply widening to it.
> + */
> + return choice_arr[loop_ctx.j];
would the test be a bit more interesting if you use loop_ctx.i here?
`return choice_arr[loop_ctx.i & 1];` ?
> +}
> +
> static int loop_detection_cb(__u32 idx, struct num_context *ctx)
> {
> for (;;) {}
> --
> 2.42.0
>
