From: "Benno Lossin" <lossin@kernel.org>
To: "Alice Ryhl" <aliceryhl@google.com>
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Andreas Hindborg" <a.hindborg@kernel.org>,
"Trevor Gross" <tmgross@umich.edu>,
"Danilo Krummrich" <dakr@kernel.org>,
rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 2/2] uaccess: rust: add UserSliceReader::strcpy_into_buf
Date: Wed, 18 Jun 2025 20:21:33 +0200 [thread overview]
Message-ID: <DAPV905HEGUN.5CLGEF6MLNWN@kernel.org> (raw)
In-Reply-To: <CAH5fLghMD2RQynaFdLVa+JAy17o5NW_pe7p3Cj1-A-FQVA--_A@mail.gmail.com>
On Tue Jun 17, 2025 at 10:55 AM CEST, Alice Ryhl wrote:
> On Tue, Jun 17, 2025 at 9:38 AM Benno Lossin <lossin@kernel.org> wrote:
>> What about the case `self.length == 0`? Will `raw_strncpy_from_user`
>> return early with a page fault, or will it return with `len == 0`?
>> Because if it is the latter, then this will result in UB.
>
> If `self.length == 0`, then you will either:
> 1. If buf.is_empty() then you return EINVAL at the top.
> 2. Otherwise, you return EFAULT from the `len < buf.len()` case.
Ah that makes sense. Thanks for explaining.
---
Cheers,
Benno
next prev parent reply other threads:[~2025-06-18 18:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-16 12:41 [PATCH v5 0/2] strncpy_from_user for Rust Alice Ryhl
2025-06-16 12:41 ` [PATCH v5 1/2] uaccess: rust: add strncpy_from_user Alice Ryhl
2025-06-16 12:41 ` [PATCH v5 2/2] uaccess: rust: add UserSliceReader::strcpy_into_buf Alice Ryhl
2025-06-17 7:38 ` Benno Lossin
2025-06-17 8:55 ` Alice Ryhl
2025-06-18 18:21 ` Benno Lossin [this message]
2025-07-13 23:37 ` [PATCH v5 0/2] strncpy_from_user for Rust Miguel Ojeda
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