linux-kernel - RE: [PATCH] tty: hvc-iucv: fix function pointer casts

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]

Date: Wed, 14 Feb 2024 09:46:33 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Segher Boessenkool' <segher@...nel.crashing.org>, Arnd Bergmann
	<arnd@...nel.org>
CC: "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>, "Arnd
 Bergmann" <arnd@...db.de>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"llvm@...ts.linux.dev" <llvm@...ts.linux.dev>, Nick Desaulniers
	<ndesaulniers@...gle.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, Nathan Chancellor <nathan@...nel.org>, "Bill
 Wendling" <morbo@...gle.com>, "linux-serial@...r.kernel.org"
	<linux-serial@...r.kernel.org>, Justin Stitt <justinstitt@...gle.com>, "Jiri
 Slaby" <jirislaby@...nel.org>
Subject: RE: [PATCH] tty: hvc-iucv: fix function pointer casts

From: Segher Boessenkool
> Sent: 13 February 2024 19:13
> 
> On Tue, Feb 13, 2024 at 11:17:49AM +0100, Arnd Bergmann wrote:
> > clang warns about explicitly casting between incompatible function
> > pointers:
> >
> > drivers/tty/hvc/hvc_iucv.c:1100:23: error: cast from 'void (*)(const void *)' to 'void (*)(struct
> device *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
> >  1100 |         priv->dev->release = (void (*)(struct device *)) kfree;
> >       |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Such a cast of course is explicitly allowed by 6.3.2.3/8, only calling a
> function using a non-compatible type is UB.  This warning message is
> quite misleading.  Doubly so because of the -Werror, as always.

But it will get called using the wrong type.
And (is it) fine-ibt will reject the incorrect call.

Has clang/gcc added an attribute to 'seed' the ibt hash yet?
So that functions that are void (*)(void) can be separated?

	David

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