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Date: Wed, 29 May 2019 08:48:08 -0700
From: Thomas Garnier <thgarnie@...omium.org>
To: Eric Biggers <ebiggers@...nel.org>
Cc: Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Kristen Carlson Accardi <kristen@...ux.intel.com>, Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>, "the arch/x86 maintainers" <x86@...nel.org>,
Linux Crypto Mailing List <linux-crypto@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 01/12] x86/crypto: Adapt assembly for PIE support
On Wed, May 22, 2019 at 1:55 PM Eric Biggers <ebiggers@...nel.org> wrote:
>
> On Wed, May 22, 2019 at 01:47:07PM -0700, Thomas Garnier wrote:
> > On Mon, May 20, 2019 at 9:06 PM Eric Biggers <ebiggers@...nel.org> wrote:
> > >
> > > On Mon, May 20, 2019 at 04:19:26PM -0700, Thomas Garnier wrote:
> > > > diff --git a/arch/x86/crypto/sha256-avx2-asm.S b/arch/x86/crypto/sha256-avx2-asm.S
> > > > index 1420db15dcdd..2ced4b2f6c76 100644
> > > > --- a/arch/x86/crypto/sha256-avx2-asm.S
> > > > +++ b/arch/x86/crypto/sha256-avx2-asm.S
> > > > @@ -588,37 +588,42 @@ last_block_enter:
> > > > mov INP, _INP(%rsp)
> > > >
> > > > ## schedule 48 input dwords, by doing 3 rounds of 12 each
> > > > - xor SRND, SRND
> > > > + leaq K256(%rip), SRND
> > > > + ## loop1 upper bound
> > > > + leaq K256+3*4*32(%rip), INP
> > > >
> > > > .align 16
> > > > loop1:
> > > > - vpaddd K256+0*32(SRND), X0, XFER
> > > > + vpaddd 0*32(SRND), X0, XFER
> > > > vmovdqa XFER, 0*32+_XFER(%rsp, SRND)
> > > > FOUR_ROUNDS_AND_SCHED _XFER + 0*32
> > > >
> > > > - vpaddd K256+1*32(SRND), X0, XFER
> > > > + vpaddd 1*32(SRND), X0, XFER
> > > > vmovdqa XFER, 1*32+_XFER(%rsp, SRND)
> > > > FOUR_ROUNDS_AND_SCHED _XFER + 1*32
> > > >
> > > > - vpaddd K256+2*32(SRND), X0, XFER
> > > > + vpaddd 2*32(SRND), X0, XFER
> > > > vmovdqa XFER, 2*32+_XFER(%rsp, SRND)
> > > > FOUR_ROUNDS_AND_SCHED _XFER + 2*32
> > > >
> > > > - vpaddd K256+3*32(SRND), X0, XFER
> > > > + vpaddd 3*32(SRND), X0, XFER
> > > > vmovdqa XFER, 3*32+_XFER(%rsp, SRND)
> > > > FOUR_ROUNDS_AND_SCHED _XFER + 3*32
> > > >
> > > > add $4*32, SRND
> > > > - cmp $3*4*32, SRND
> > > > + cmp INP, SRND
> > > > jb loop1
> > > >
> > > > + ## loop2 upper bound
> > > > + leaq K256+4*4*32(%rip), INP
> > > > +
> > > > loop2:
> > > > ## Do last 16 rounds with no scheduling
> > > > - vpaddd K256+0*32(SRND), X0, XFER
> > > > + vpaddd 0*32(SRND), X0, XFER
> > > > vmovdqa XFER, 0*32+_XFER(%rsp, SRND)
> > > > DO_4ROUNDS _XFER + 0*32
> > > >
> > > > - vpaddd K256+1*32(SRND), X1, XFER
> > > > + vpaddd 1*32(SRND), X1, XFER
> > > > vmovdqa XFER, 1*32+_XFER(%rsp, SRND)
> > > > DO_4ROUNDS _XFER + 1*32
> > > > add $2*32, SRND
> > > > @@ -626,7 +631,7 @@ loop2:
> > > > vmovdqa X2, X0
> > > > vmovdqa X3, X1
> > > >
> > > > - cmp $4*4*32, SRND
> > > > + cmp INP, SRND
> > > > jb loop2
> > > >
> > > > mov _CTX(%rsp), CTX
> > >
> > > There is a crash in sha256-avx2-asm.S with this patch applied. Looks like the
> > > %rsi register is being used for two different things at the same time: 'INP' and
> > > 'y3'? You should be able to reproduce by booting a kernel configured with:
> > >
> > > CONFIG_CRYPTO_SHA256_SSSE3=y
> > > # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
> >
> > Thanks for testing the patch. I couldn't reproduce this crash, can you
> > share the whole .config or share any other specifics of your testing
> > setup?
> >
>
> I attached the .config I used. It reproduces on v5.2-rc1 with just this patch
> applied. The machine you're using does have AVX2 support, right? If you're
> using QEMU, did you make sure to pass '-cpu host'?
Thanks for your help offline on this Eric. I was able to repro the
issue and fix it, it will be part of the next iteration. You were
right that esi was used later on, I simplified the code in this
context and ran more testing on all CONFIG_CRYPTO_* options.
>
> - Eric
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