From: Bart Van Assche <bvanassche@acm.org>
To: Deepanshu Kartikey <kartikey406@gmail.com>,
axboe@kernel.dk, rostedt@goodmis.org, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH v2] blktrace: reject buf_size smaller than blk_io_trace2
Date: Sun, 3 May 2026 13:08:47 +0200 [thread overview]
Message-ID: <8abcd4ec-3e62-49d8-8657-f1a1ca925fba@acm.org> (raw)
In-Reply-To: <20260503085519.138360-1-kartikey406@gmail.com>
On 5/3/26 10:55 AM, Deepanshu Kartikey wrote:
> blk_trace_setup() accepts any non-zero buf_size from
> userspace and passes it directly to relay_open(). If
> buf_size is smaller than sizeof(struct blk_io_trace2),
> relay_reserve() always returns NULL and all trace
> events are silently dropped.
That's the intended behavior, isn't it?
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 8cd2520b4c99..20f941495151 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -773,7 +773,7 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
> if (ret)
> return -EFAULT;
>
> - if (!buts.buf_size || !buts.buf_nr)
> + if (buts.buf_size < sizeof(struct blk_io_trace2) || !buts.buf_nr)
> return -EINVAL;
>
> buts2 = (struct blk_user_trace_setup2) {
We may be better off not changing this code because there may be users
who rely on the current behavior and who will report this change in
behavior as a regression.
Thanks,
Bart.
prev parent reply other threads:[~2026-05-03 11:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-03 8:55 [PATCH v2] blktrace: reject buf_size smaller than blk_io_trace2 Deepanshu Kartikey
2026-05-03 11:08 ` Bart Van Assche [this message]
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