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From: David Laight <David.Laight@ACULAB.COM>
To: 'Andreas Fink' <afink@list.fink.org>,
	Dan Carpenter <dan.carpenter@oracle.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>,
	Xin Long <lucien.xin@gmail.com>,
	"Neil Horman" <nhorman@tuxdriver.com>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"linux-sctp@vger.kernel.org" <linux-sctp@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"kernel-janitors@vger.kernel.org"
	<kernel-janitors@vger.kernel.org>
Subject: RE: [PATCH net] sctp: prevent info leak in sctp_make_heartbeat()
Date: Tue, 29 Jun 2021 10:37:48 +0000	[thread overview]
Message-ID: <c76a03be72ae4dfc9b6a65d418d699e2@AcuMS.aculab.com> (raw)
In-Reply-To: <886e4daf-c239-c1ce-da52-4b4684449908@list.fink.org>

> > -	struct sctp_sender_hb_info hbinfo;
> > +	struct sctp_sender_hb_info hbinfo = {};

> Does that gcc extension work with all compilers, especially clang?

> > So that's nice, because adding memset()s to zero everywhere was ugly.

The 'real fun' (tm) starts when the bit pattern for the NULL
pointer isn't 'all zeros'.
Using memset() is then broken - I suspect the compiler is
expected to initialise pointers to the correct NULL pattern.

Not that I think anyone sane would consider trying to compile
any 'normal' C code for such a system.

OTOH it is probably why clang is bleating about (int)((char *)0 + 4)
being undefined behaviour.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

      parent reply	other threads:[~2021-06-29 10:37 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-29  8:19 [PATCH net] sctp: prevent info leak in sctp_make_heartbeat() Dan Carpenter
2021-06-29  8:23 ` Andreas Fink
2021-06-29  9:13   ` Dan Carpenter
2021-06-29 10:37   ` David Laight [this message]

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