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Date: Wed, 22 May 2019 13:47:07 -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 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?

>
> Crash report:
>
> BUG: unable to handle page fault for address: ffffc8ff83b21a80
> #PF: supervisor write access in kernel mode
> #PF: error_code(0x0002) - not-present page
> PGD 0 P4D 0
> Oops: 0002 [#1] SMP
> CPU: 3 PID: 359 Comm: cryptomgr_test Not tainted 5.2.0-rc1-00109-g9fb4fd100429b #5
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014
> RIP: 0010:loop1+0x4/0x888
> Code: 83 c6 40 48 89 b4 24 08 02 00 00 48 8d 3d 94 d3 d0 00 48 8d 35 0d d5 d0 00 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 c
> RSP: 0018:ffffc90001d43880 EFLAGS: 00010286
> RAX: 000000006a09e667 RBX: 00000000bb67ae85 RCX: 000000003c6ef372
> RDX: 00000000510e527f RSI: ffffffff81dde380 RDI: ffffffff81dde200
> RBP: ffffc90001d43b10 R08: 00000000a54ff53a R09: 000000009b05688c
> R10: 000000001f83d9ab R11: 000000005be0cd19 R12: 0000000000000000
> R13: ffff88807cfd4598 R14: ffffffff810d0da0 R15: ffffc90001d43cc0
> FS:  0000000000000000(0000) GS:ffff88807fd80000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffc8ff83b21a80 CR3: 000000000200f000 CR4: 00000000003406e0
> Call Trace:
>  sha256_avx2_finup arch/x86/crypto/sha256_ssse3_glue.c:242 [inline]
>  sha256_avx2_final+0x17/0x20 arch/x86/crypto/sha256_ssse3_glue.c:247
>  crypto_shash_final+0x13/0x20 crypto/shash.c:166
>  shash_async_final+0x11/0x20 crypto/shash.c:265
>  crypto_ahash_op+0x24/0x60 crypto/ahash.c:373
>  crypto_ahash_final+0x11/0x20 crypto/ahash.c:384
>  do_ahash_op.constprop.13+0x10/0x40 crypto/testmgr.c:1049
>  test_hash_vec_cfg+0x5b1/0x610 crypto/testmgr.c:1225
>  test_hash_vec crypto/testmgr.c:1268 [inline]
>  __alg_test_hash.isra.8+0x115/0x1d0 crypto/testmgr.c:1498
>  alg_test_hash+0x7b/0x100 crypto/testmgr.c:1546
>  alg_test.part.12+0xa4/0x360 crypto/testmgr.c:4931
>  alg_test+0x12/0x30 crypto/testmgr.c:4895
>  cryptomgr_test+0x26/0x50 crypto/algboss.c:223
>  kthread+0x124/0x140 kernel/kthread.c:254
>  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
> Modules linked in:
> CR2: ffffc8ff83b21a80
> ---[ end trace ee8ece604888de3e ]---
>
> - Eric

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