linux-kernel - Re: BUG: KASAN: stack-out-of-bounds in unwind_next

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Date:   Thu, 4 Feb 2021 11:51:44 -0800
From:   Ivan Babrou <ivan@...udflare.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     kernel-team <kernel-team@...udflare.com>,
        Ignat Korchagin <ignat@...udflare.com>,
        Hailong liu <liu.hailong6@....com.cn>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Julien Thierry <jthierry@...hat.com>,
        Jiri Slaby <jirislaby@...nel.org>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-kernel <linux-kernel@...r.kernel.org>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Robert Richter <rric@...nel.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        bpf@...r.kernel.org, Alexey Kardashevskiy <aik@...abs.ru>
Subject: Re: BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x1df5/0x2650

On Wed, Feb 3, 2021 at 4:17 PM Josh Poimboeuf <jpoimboe@...hat.com> wrote:
>
> On Wed, Feb 03, 2021 at 03:30:35PM -0800, Ivan Babrou wrote:
> > > > > Can you recreate with this patch, and add "unwind_debug" to the cmdline?
> > > > > It will spit out a bunch of stack data.
> > > >
> > > > Here's the three I'm building:
> > > >
> > > > * https://github.com/bobrik/linux/tree/ivan/static-call-5.9
> > > >
> > > > It contains:
> > > >
> > > > * v5.9 tag as the base
> > > > * static_call-2020-10-12 tag
> > > > * dm-crypt patches to reproduce the issue with KASAN
> > > > * x86/unwind: Add 'unwind_debug' cmdline option
> > > > * tracepoint: Fix race between tracing and removing tracepoint
> > > >
> > > > The very same issue can be reproduced on 5.10.11 with no patches,
> > > > but I'm going with 5.9, since it boils down to static call changes.
> > > >
> > > > Here's the decoded stack from the kernel with unwind debug enabled:
> > > >
> > > > * https://gist.github.com/bobrik/ed052ac0ae44c880f3170299ad4af56b
> > > >
> > > > See my first email for the exact commands that trigger this.
> > >
> > > Thanks.  Do you happen to have the original dmesg, before running it
> > > through the post-processing script?
> >
> > Yes, here it is:
> >
> > * https://gist.github.com/bobrik/8c13e6a02555fb21cadabb74cdd6f9ab
>
> It appears the unwinder is getting lost in crypto code.  No idea what
> this has to do with static calls though.  Or maybe you're seeing
> multiple issues.
>
> Does this fix it?
>
>
> diff --git a/arch/x86/crypto/Makefile b/arch/x86/crypto/Makefile
> index a31de0c6ccde..36c55341137c 100644
> --- a/arch/x86/crypto/Makefile
> +++ b/arch/x86/crypto/Makefile
> @@ -2,7 +2,14 @@
>  #
>  # x86 crypto algorithms
>
> -OBJECT_FILES_NON_STANDARD := y
> +OBJECT_FILES_NON_STANDARD_sha256-avx2-asm.o            := y
> +OBJECT_FILES_NON_STANDARD_sha512-ssse3-asm.o           := y
> +OBJECT_FILES_NON_STANDARD_sha512-avx-asm.o             := y
> +OBJECT_FILES_NON_STANDARD_sha512-avx2-asm.o            := y
> +OBJECT_FILES_NON_STANDARD_crc32c-pcl-intel-asm_64.o    := y
> +OBJECT_FILES_NON_STANDARD_camellia-aesni-avx2-asm_64.o := y
> +OBJECT_FILES_NON_STANDARD_sha1_avx2_x86_64_asm.o       := y
> +OBJECT_FILES_NON_STANDARD_sha1_ni_asm.o                        := y
>
>  obj-$(CONFIG_CRYPTO_GLUE_HELPER_X86) += glue_helper.o
>
> diff --git a/arch/x86/crypto/aesni-intel_avx-x86_64.S b/arch/x86/crypto/aesni-intel_avx-x86_64.S
> index 5fee47956f3b..59c36b88954f 100644
> --- a/arch/x86/crypto/aesni-intel_avx-x86_64.S
> +++ b/arch/x86/crypto/aesni-intel_avx-x86_64.S
> @@ -237,8 +237,8 @@ define_reg j %j
>  .noaltmacro
>  .endm
>
> -# need to push 4 registers into stack to maintain
> -STACK_OFFSET = 8*4
> +# need to push 5 registers into stack to maintain
> +STACK_OFFSET = 8*5
>
>  TMP1 =   16*0    # Temporary storage for AAD
>  TMP2 =   16*1    # Temporary storage for AES State 2 (State 1 is stored in an XMM register)
> @@ -257,6 +257,8 @@ VARIABLE_OFFSET = 16*8
>
>  .macro FUNC_SAVE
>          #the number of pushes must equal STACK_OFFSET
> +       push    %rbp
> +       mov     %rsp, %rbp
>          push    %r12
>          push    %r13
>          push    %r14
> @@ -271,12 +273,14 @@ VARIABLE_OFFSET = 16*8
>  .endm
>
>  .macro FUNC_RESTORE
> +        add     $VARIABLE_OFFSET, %rsp
>          mov     %r14, %rsp
>
>          pop     %r15
>          pop     %r14
>          pop     %r13
>          pop     %r12
> +       pop     %rbp
>  .endm
>
>  # Encryption of a single block
>

This patch seems to fix the following warning:

[  147.995699][    C0] WARNING: stack going in the wrong direction? at
glue_xts_req_128bit+0x21f/0x6f0 [glue_helper]

Or at least I cannot see it anymore when combined with your other
patch, not sure if it did the trick by itself.

This sounds like a good reason to send them both.