linux-kernel - bpf: ensure all memory is initialized in bpf_get_current

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Message-ID: <20230405225246.1327344-1-brho@google.com>
Date:   Wed,  5 Apr 2023 18:52:46 -0400
From:   Barret Rhoden <brho@...gle.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: bpf: ensure all memory is initialized in bpf_get_current_comm

BPF helpers that take an ARG_PTR_TO_UNINIT_MEM must ensure that all of
the memory is set, including beyond the end of the string.

Signed-off-by: Barret Rhoden <brho@...gle.com>
---
 kernel/bpf/helpers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 5b278a38ae58..adffb2f87e44 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -257,7 +257,7 @@ BPF_CALL_2(bpf_get_current_comm, char *, buf, u32, size)
 		goto err_clear;
 
 	/* Verifier guarantees that size > 0 */
-	strscpy(buf, task->comm, size);
+	strscpy_pad(buf, task->comm, size);
 	return 0;
 err_clear:
 	memset(buf, 0, size);
-- 
2.40.0.348.gf938b09366-goog