linux-kernel - [PATCH bpf-next] bpf: Replace strncpy() with strscpy

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Date:   Thu,  3 Mar 2022 16:18:00 +0800
From:   Yuntao Wang <ytcoode@...il.com>
To:     bpf@...r.kernel.org
Cc:     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>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yuntao Wang <ytcoode@...il.com>
Subject: [PATCH bpf-next] bpf: Replace strncpy() with strscpy_pad()

Using strncpy() on NUL-terminated strings is considered deprecated[1],
replace it with strscpy_pad().

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings

Signed-off-by: Yuntao Wang <ytcoode@...il.com>
---
 kernel/bpf/helpers.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index ae64110a98b5..d03b28761a67 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -225,13 +225,7 @@ BPF_CALL_2(bpf_get_current_comm, char *, buf, u32, size)
 	if (unlikely(!task))
 		goto err_clear;
 
-	strncpy(buf, task->comm, size);
-
-	/* Verifier guarantees that size > 0. For task->comm exceeding
-	 * size, guarantee that buf is %NUL-terminated. Unconditionally
-	 * done here to save the size test.
-	 */
-	buf[size - 1] = 0;
+	strscpy_pad(buf, task->comm, size);
 	return 0;
 err_clear:
 	memset(buf, 0, size);
-- 
2.35.1