From: Yuntao Wang Date: Fri, 4 Mar 2022 07:04:08 +0000 (+0800) Subject: bpf: Replace strncpy() with strscpy() X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=03b9c7fa3f15f51bcd07f3828c2a01311e7746c4;p=uclinux-h8%2Flinux.git bpf: Replace strncpy() with strscpy() Using strncpy() on NUL-terminated strings is considered deprecated[1]. Moreover, if the length of 'task->comm' is less than the destination buffer size, strncpy() will NUL-pad the destination buffer, which is a needless performance penalty. Replacing strncpy() with strscpy() fixes all these issues. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings Signed-off-by: Yuntao Wang Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20220304070408.233658-1-ytcoode@gmail.com --- diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index ae64110a98b5..315053ef6a75 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -225,13 +225,8 @@ 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; + /* Verifier guarantees that size > 0 */ + strscpy(buf, task->comm, size); return 0; err_clear: memset(buf, 0, size);