From: David Laight <David.Laight@ACULAB.COM>
To: 'Alejandro Colomar' <alx@kernel.org>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Kees Cook <keescook@chromium.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
"linux-hardening@vger.kernel.org"
<linux-hardening@vger.kernel.org>
Subject: RE: struct_size() using sizeof() vs offsetof()
Date: Mon, 21 Aug 2023 08:38:43 +0000 [thread overview]
Message-ID: <d3c4c953c9a742ae98ae9b9036561b38@AcuMS.aculab.com> (raw)
In-Reply-To: <df8fdd4a-490f-6b2a-03b6-0333e3302dce@kernel.org>
From: Alejandro Colomar <alx@kernel.org>
> Sent: Thursday, August 17, 2023 7:38 PM
>
> Hi Gustavo,
>
> On 2023-08-17 18:05, Gustavo A. R. Silva wrote:
> >
> >> - tp_c = kzalloc(sizeof(*tp_c), GFP_KERNEL);
> >> + tp_c = kzalloc(struct_size(tp_c, hlist->ht, 1), GFP_KERNEL);
> >
> > I just sent a fix[1].
> >
> > Thanks for reporting this! :)
Perhaps struct_size() should include an assertion that:
(offsetof(type, field[8]) > sizeof (type))
That will ensure that field is an array member and reasonably
near the end of the structure.
A more complex calculation (using _Alignof(type) and the offset/size
of field) could be used.
But I don't think you can actually detect it is field[] (or even the
last member).
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2023-08-21 8:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <74e8cf91-d095-33e3-c548-34d80b691089@kernel.org>
2023-08-17 3:05 ` struct_size() using sizeof() vs offsetof() Kees Cook
2023-08-17 12:39 ` Alejandro Colomar
2023-08-17 16:05 ` Gustavo A. R. Silva
2023-08-17 18:37 ` Alejandro Colomar
2023-08-21 8:38 ` David Laight [this message]
2023-08-21 13:51 ` Alejandro Colomar
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