netdev - [PATCH bpf-next v2 4/7] bpf: verifier: reorder stack size check with dead code sanitization

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Date:   Wed, 19 Dec 2018 22:13:06 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH bpf-next v2 4/7] bpf: verifier: reorder stack size check with dead code sanitization

Reorder the calls to check_max_stack_depth() and sanitize_dead_code()
to separate functions which can rewrite instructions from pure checks.

No functional changes.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Jiong Wang <jiong.wang@...ronome.com>
---
 kernel/bpf/verifier.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 98ed27bbd045..d27d5a880015 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6983,10 +6983,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 	free_states(env);
 
 	if (ret == 0)
-		sanitize_dead_code(env);
+		ret = check_max_stack_depth(env);
 
+	/* instruction rewrites happen after this point */
 	if (ret == 0)
-		ret = check_max_stack_depth(env);
+		sanitize_dead_code(env);
 
 	if (ret == 0)
 		/* program is valid, convert *(u32*)(ctx + off) accesses */
-- 
2.19.2