linux-kernel - [PATCH bpf-next v7 03/24] bpf/verifier: do not clear meta in check_mem

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Date:   Thu, 21 Jul 2022 17:36:04 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Jiri Kosina <jikos@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Kumar Kartikeya Dwivedi <memxor@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
        Dave Marchevsky <davemarchevsky@...com>,
        Joe Stringer <joe@...ium.io>, Jonathan Corbet <corbet@....net>
Cc:     Tero Kristo <tero.kristo@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: [PATCH bpf-next v7 03/24] bpf/verifier: do not clear meta in check_mem_size

The purpose of this clear is to prevent meta->raw_mode to be evaluated
at true, but this also prevents to forward any other data to the other
callees.

Only switch back raw_mode to false so we don't entirely clear meta.

Acked-by: Yonghong Song <yhs@...com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

---

no changes in v7

new in v6
---
 kernel/bpf/verifier.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d5fe7e618c52..92714299831c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5282,7 +5282,7 @@ static int check_mem_size_reg(struct bpf_verifier_env *env,
 		 * initialize all the memory that the helper could
 		 * just partially fill up.
 		 */
-		meta = NULL;
+		meta->raw_mode = false;
 
 	if (reg->smin_value < 0) {
 		verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
-- 
2.36.1