selftests/bpf: test widening for iterating callbacks

commit 9f3330aa644d6d979eb064c46e85c62d4b4eac75 upstream.

A test case to verify that imprecise scalars widening is applied to
callback entering state, when callback call is simulated repeatedly.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-10-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
index fa9429f..598c1e9 100644 (file)
--- 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];
+}
+
 static int loop_detection_cb(__u32 idx, struct num_context *ctx)
 {
        for (;;) {}