From: Andrii Nakryiko <andrii@kernel.org>
Date: Sat, 2 Dec 2023 17:57:02 +0000 (-0800)
Subject: bpf: enforce precision of R0 on program/async callback return
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=eabe518de533a4291996020977054a7a7b78c7d3;p=linux.git

bpf: enforce precision of R0 on program/async callback return

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@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c54944af1bccb..2cd150d6d141e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -15138,6 +15138,10 @@ enforce_retval:
 		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 &&