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selftests/bpf: test widening for iterating callbacks

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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>
This commit is contained in:
Eduard Zingerman 2023-11-21 04:06:59 +02:00 • committed by Alexei Starovoitov
parent cafe2c2150
commit 9f3330aa64
1 changed files with 20 additions and 0 deletions
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20
tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
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@ -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 (;;) {}