[PATCH v4 bpf-next 08/11] bpf: enforce precision of R0 on program/async callback return

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Given we enforce a valid range for program and async callback return
value, we must mark R0 as precise to avoid incorrect state pruning.

Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking")
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
 kernel/bpf/verifier.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c54944af1bcc..2cd150d6d141 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -15138,6 +15138,10 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char
 		return -EINVAL;
 	}
 
+	err = mark_chain_precision(env, regno);
+	if (err)
+		return err;
+
 	if (!retval_range_within(range, reg)) {
 		verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name);
 		if (!is_subprog &&
-- 
2.34.1






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