linux-kernel - Re: [PATCH v2 1/1] futex: remove duplicated code and fix UB

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:   Fri, 25 Aug 2017 22:43:41 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Will Deacon <will.deacon@....com>
cc:     Jiri Slaby <jslaby@...e.cz>, mingo@...hat.com,
        dvhart@...radead.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        Vineet Gupta <vgupta@...opsys.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Richard Kuo <rkuo@...eaurora.org>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Michal Simek <monstr@...str.eu>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        "James E.J. Bottomley" <jejb@...isc-linux.org>,
        Helge Deller <deller@....de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        "H. Peter Anvin" <hpa@...or.com>, Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        Arnd Bergmann <arnd@...db.de>, x86@...nel.org,
        linux-alpha@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
        linux-mips@...ux-mips.org, openrisc@...ts.librecores.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
        sparclinux@...r.kernel.org, linux-xtensa@...ux-xtensa.org,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH v2 1/1] futex: remove duplicated code and fix UB

On Thu, 24 Aug 2017, Will Deacon wrote:
> On Thu, Aug 24, 2017 at 09:31:05AM +0200, Jiri Slaby wrote:
> > +static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
> > +{
> > +	unsigned int op =	  (encoded_op & 0x70000000) >> 28;
> > +	unsigned int cmp =	  (encoded_op & 0x0f000000) >> 24;
> > +	int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 12);
> > +	int cmparg = sign_extend32(encoded_op & 0x00000fff, 12);
> > +	int oldval, ret;
> > +
> > +	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) {
> > +		if (oparg < 0 || oparg > 31)
> > +			return -EINVAL;
> > +		oparg = 1 << oparg;
> > +	}
> > +
> > +	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
> > +		return -EFAULT;
> > +
> > +	ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr);
> > +	if (ret)
> > +		return ret;
> 
> We could move the pagefault_{disable,enable} calls here, and then remove
> them from the futex_atomic_op_inuser callsites elsewhere in futex.c

Correct, but we can do that after getting this in.

Thanks,

	tglx