linux-kernel - Re: [PATCH] io_uring/uring_cmd: add missing READ

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4bf7e5d1-4e66-496d-a503-5dc349efe398@kernel.dk>
Date: Wed, 22 Jan 2025 17:18:22 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Pavel Begunkov <asml.silence@...il.com>, Jann Horn <jannh@...gle.com>
Cc: io-uring@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] io_uring/uring_cmd: add missing READ_ONCE() on shared
 memory read

On 1/22/25 12:38 PM, Jens Axboe wrote:
> 
> On Tue, 21 Jan 2025 17:09:59 +0100, Jann Horn wrote:
>> cmd->sqe seems to point to shared memory here; so values should only be
>> read from it with READ_ONCE(). To ensure that the compiler won't generate
>> code that assumes the value in memory will stay constant, add a
>> READ_ONCE().
>> The callees io_uring_cmd_getsockopt() and io_uring_cmd_setsockopt() already
>> do this correctly.
>>
>> [...]
> 
> Applied, thanks!
> 
> [1/1] io_uring/uring_cmd: add missing READ_ONCE() on shared memory read
>       commit: 0963dba3dc006b454c54fd019bbbdb931e7a7c70

I took a closer look and this isn't necessary. Either ->sqe is a full
copy at this point. Should probably be renamed as such... If we want to
make this clearer, then we should do:

-       switch (cmd->sqe->cmd_op) {
+       switch (cmd->cmd_op) {

instead.

I'll drop this one.

-- 
Jens Axboe