From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9762023BF83 for ; Thu, 3 Jul 2025 16:03:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751558628; cv=none; b=EliyGXRH2FdFnj7WdjqhPO7+ouvbiW94rqFsQMnIAhwVp8zrRVIZ+iTQlMiZaY+aEk6YoX5tvsDzZQpRv9IQu6/g8Q2+A3lwiydKV11ZHR9Q4TOm4ZoPg0I2/nZ/9qeR0Nq0Zg0V1PFh5O5bgU5RdTGKopOi8APCUOZICEiW4DU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751558628; c=relaxed/simple; bh=45no1ZSRP9ZgISPSug/hQGZSvkJCKpkWro/E23xCXnE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JGCQjJr3gNCMCklVsG6Tj0tI829u3VUVZP9WKoxX65VyKb47SfjtEgFjOLrNI423J2G2xKADdcnGSgA8q6aP3Eo1LVV9kFO1CuFwKsTdXKPzE5bSQ1rd+uU1D/2Xl7WO/Yh0qQknzmo03ScMnRTXFXFx7G+/kMserjmErzCBrLQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=iUwkEbhj; arc=none smtp.client-ip=95.215.58.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="iUwkEbhj" Message-ID: <9447cc50-03be-4eba-809d-f9e3381654fa@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1751558624; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tcnfgrgLziJsJtGNHM11WwOgZeqfNsbwcjttOSUdxs8=; b=iUwkEbhjj7s7uRc1RrA/nf302Yc52VWq8yVDQ7fVYOj7dkpR3K/iX5y2IelMvzQ6qgPOhR zD5BRsL2JmZKNiTUV+xmfN5iu+r8rS/HnhcQOdDMvnrpCSvEmjqzVO+VQlW32BpX6lb5zv AycfcLxmEmwqcO8FFj7cQJlkQnZoheY= Date: Fri, 4 Jul 2025 00:03:33 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next] bpf: Clean code with bpf_copy_to_user To: Yonghong Song , ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250703124336.672416-1-chen.dylane@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Tao Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 在 2025/7/3 23:35, Yonghong Song 写道: > > > On 7/3/25 5:43 AM, Tao Chen wrote: >> No logic change, just use bpf_copy_to_user to clean code. >> >> Signed-off-by: Tao Chen >> --- >>   kernel/bpf/syscall.c | 17 +++-------------- >>   1 file changed, 3 insertions(+), 14 deletions(-) >> >> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c >> index e6eea594f1c..ca152d36312 100644 >> --- a/kernel/bpf/syscall.c >> +++ b/kernel/bpf/syscall.c >> @@ -5208,21 +5208,10 @@ static int bpf_task_fd_query_copy(const union >> bpf_attr *attr, >>               if (put_user(zero, ubuf)) >>                   return -EFAULT; >> -        } else if (input_len >= len + 1) { >> -            /* ubuf can hold the string with NULL terminator */ >> -            if (copy_to_user(ubuf, buf, len + 1)) >> -                return -EFAULT; >>           } else { >> -            /* ubuf cannot hold the string with NULL terminator, >> -             * do a partial copy with NULL terminator. >> -             */ >> -            char zero = '\0'; >> - >> -            err = -ENOSPC; >> -            if (copy_to_user(ubuf, buf, input_len - 1)) >> -                return -EFAULT; >> -            if (put_user(zero, ubuf + input_len - 1)) >> -                return -EFAULT; >> +            err = bpf_copy_to_user(ubuf, buf, input_len, len); >> +            if (err) >> +                return err; >>           } >>       } > > Actually, there is a return value change with this patch. > bpf_copy_to_user() return returns -ENOSPC while the original > implementation may return -EFAULT due to following code. > >         if (put_user(prog_id, &uattr->task_fd_query.prog_id) || >             put_user(fd_type, &uattr->task_fd_query.fd_type) || >             put_user(probe_offset, &uattr->task_fd_query.probe_offset) || >             put_user(probe_addr, &uattr->task_fd_query.probe_addr)) >                 return -EFAULT; > >         return err; > You are right, maybe we can just use: err = bpf_copy_to_user(ubuf, buf, input_len, len); and no return check or move these put_user code to the front. -- Best Regards Tao Chen