From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Sidong Yang <sidong.yang@furiosa.ai>
Cc: Jens Axboe <axboe@kernel.dk>,
Daniel Almeida <daniel.almeida@collabora.com>,
Caleb Sander Mateos <csander@purestorage.com>,
Benno Lossin <lossin@kernel.org>, Miguel Ojeda <ojeda@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
io-uring@vger.kernel.org
Subject: Re: [PATCH v4 2/5] io_uring/cmd: zero-init pdu in io_uring_cmd_prep() to avoid UB
Date: Thu, 9 Apr 2026 07:27:18 +0200 [thread overview]
Message-ID: <2026040908-certainly-dealmaker-5530@gregkh> (raw)
In-Reply-To: <20260408140007.8401-3-sidong.yang@furiosa.ai>
On Wed, Apr 08, 2026 at 01:59:59PM +0000, Sidong Yang wrote:
> The pdu field in io_uring_cmd may contain stale data when a request
> object is recycled from the slab cache. Accessing uninitialized or
> garbage memory can lead to undefined behavior in users of the pdu.
Who accesses this? If that happens, then yes this is a problem, but if
not, then there's no need for this change, right (i.e. either this is a
bug to be fixed now or not.)
> Ensure the pdu buffer is cleared during io_uring_cmd_prep() so that
> each command starts from a well-defined state. This avoids exposing
> uninitialized memory and prevents potential misinterpretation of data
> from previous requests.
Where is the memory exposed and who misinterprets it?
> No functional change is intended other than guaranteeing that pdu is
> always zero-initialized before use.
This strongly implies that this is not needed at all.
thanks,
greg k-h
next prev parent reply other threads:[~2026-04-09 5:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-08 13:59 [PATCH v4 0/5] Rust io_uring command abstraction for miscdevice Sidong Yang
2026-04-08 13:59 ` [PATCH v4 1/5] rust: bindings: add io_uring headers in bindings_helper.h Sidong Yang
2026-04-08 14:31 ` Miguel Ojeda
2026-04-09 1:20 ` Sidong Yang
2026-04-08 13:59 ` [PATCH v4 2/5] io_uring/cmd: zero-init pdu in io_uring_cmd_prep() to avoid UB Sidong Yang
2026-04-09 5:27 ` Greg Kroah-Hartman [this message]
2026-04-08 14:00 ` [PATCH v4 3/5] rust: io_uring: introduce rust abstraction for io-uring cmd Sidong Yang
2026-04-08 14:00 ` [PATCH v4 4/5] rust: miscdevice: Add `uring_cmd` support Sidong Yang
2026-04-08 14:00 ` [PATCH v4 5/5] samples: rust: Add `uring_cmd` example to `rust_misc_device` Sidong Yang
2026-04-09 5:25 ` [PATCH v4 0/5] Rust io_uring command abstraction for miscdevice Greg Kroah-Hartman
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