From: Dan Carpenter <dan.carpenter@linaro.org>
To: Marc Herbert <marc.herbert@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
Greg KH <gregkh@linuxfoundation.org>,
Miguel Ojeda <ojeda@kernel.org>,
Benjamin.Cheatham@amd.com, Jonathan.Cameron@huawei.com,
dakr@kernel.org, linux-acpi@vger.kernel.org,
linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org,
rafael.j.wysocki@intel.com, rafael@kernel.org,
sudeep.holla@arm.com, Kees Cook <kees@kernel.org>
Subject: Re: [PATCH] driver core: faux: fix Undefined Behavior in faux_device_destroy()
Date: Thu, 19 Jun 2025 07:02:25 +0300 [thread overview]
Message-ID: <d478fbca-e98d-4a16-9298-01dcaa8bb008@suswa.mountain> (raw)
In-Reply-To: <206ebae8-4e2d-4e04-8872-fa3a56b3e398@linux.intel.com>
On Wed, Jun 18, 2025 at 08:33:27PM -0700, Marc Herbert wrote:
> > But, again, this is a totally different thing from what the patch does.
> > The faux_device_destroy() code is not doing a dereference, it's doing
> > pointer math.
>
> pointer math is what we _want_ the code to do. But if that relies on
> some undefined behavior(s) then the bets are off again. Check
> https://stackoverflow.com/questions/26906621/does-struct-name-null-b-cause-undefined-behaviour-in-c11
> where offsetof() is a suggested alternative.
The answers talk about "But the value of a null pointer constant is not
defined as 0." which is some trivia that had heard before. Probably
I heard it in the context of someone saying that we should check
"if (p == NULL)" instead of "if (!p)"...
regards,
dan carpenter
next prev parent reply other threads:[~2025-06-19 4:02 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-13 19:15 [PATCH] driver core: faux: fix Undefined Behavior in faux_device_destroy() marc.herbert
2025-06-13 20:20 ` Miguel Ojeda
2025-06-14 0:33 ` Greg KH
2025-06-14 10:50 ` Miguel Ojeda
2025-06-14 11:53 ` Greg KH
2025-06-14 14:53 ` Marc Herbert
2025-06-16 3:35 ` Greg KH
2025-06-16 14:02 ` Alice Ryhl
2025-06-18 23:43 ` Marc Herbert
2025-06-19 0:23 ` Dan Williams
2025-06-19 2:35 ` Dan Carpenter
2025-06-19 3:33 ` Marc Herbert
2025-06-19 4:02 ` Dan Carpenter [this message]
2025-06-26 0:55 ` Kent Overstreet
2025-06-30 23:24 ` Marc Herbert
2025-06-25 15:20 ` Dan Carpenter
2025-06-25 22:30 ` Marc Herbert
2025-06-25 23:18 ` Dan Carpenter
2025-06-25 15:21 ` Dan Carpenter
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