From: Jann Horn <jannh@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
kernel list <linux-kernel@vger.kernel.org>,
Andrey Konovalov <andreyknvl@google.com>,
Andy Lutomirski <luto@kernel.org>,
Sean Christopherson <sean.j.christopherson@intel.com>
Subject: Re: [PATCH v6 4/4] x86/kasan: Print original address on #GP
Date: Wed, 18 Dec 2019 23:33:54 +0100 [thread overview]
Message-ID: <CAG48ez1-u8DbxSAu9DXTEEy3-ADquQLWXB6ufV+By7TnuxWOsQ@mail.gmail.com> (raw)
In-Reply-To: <20191211173711.GF14821@zn.tnic>
On Wed, Dec 11, 2019 at 6:37 PM Borislav Petkov <bp@alien8.de> wrote:
> On Mon, Dec 09, 2019 at 03:31:20PM +0100, Jann Horn wrote:
> > arch/x86/kernel/traps.c | 12 ++++++++++-
> > arch/x86/mm/kasan_init_64.c | 21 -------------------
> > include/linux/kasan.h | 6 ++++++
> > mm/kasan/report.c | 40 +++++++++++++++++++++++++++++++++++++
> > 4 files changed, 57 insertions(+), 22 deletions(-)
>
> I need a KASAN person ACK here, I'd guess.
Right, I got a Reviewed-by from Dmitry for v2, but cleared that when I
made changes to the patch later - I'll ask Dmitry for a fresh ack on
the v7 patch.
[...]
> > - die(desc, regs, error_code);
> > + flags = oops_begin();
> > + sig = SIGSEGV;
> > + __die_header(desc, regs, error_code);
> > + if (hint == GP_NON_CANONICAL)
> > + kasan_non_canonical_hook(gp_addr);
> > + if (__die_body(desc, regs, error_code))
> > + sig = 0;
> > + oops_end(flags, regs, sig);
>
> Instead of opencoding it like this, can we add a
>
> die_addr(desc, regs, error_code, gp_addr);
>
> to arch/x86/kernel/dumpstack.c and call it from here:
>
> if (hint != GP_NON_CANONICAL)
> gp_addr = 0;
>
> die_addr(desc, regs, error_code, gp_addr);
Okay, so I'll make __die_header() and __die_body() static, introduce
and hook up die_addr() in patch 3/4, and then in patch 4/4 insert the
call to the KASAN hook.
> This way you won't need to pass down to die_addr() the hint too - you
> code into gp_addr whether it was non-canonical or not.
>
> The
>
> + if (addr < KASAN_SHADOW_OFFSET)
> + return;
>
> check in kasan_non_canonical_hook() would then catch it when addr == 0.
I'll add an explicit check for nonzero address before calling
kasan_non_canonical_hook() so that the semantics are a bit more
cleanly split.
prev parent reply other threads:[~2019-12-18 22:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 14:31 [PATCH v6 1/4] x86/insn-eval: Add support for 64-bit kernel mode Jann Horn
2019-12-09 14:31 ` [PATCH v6 2/4] x86/traps: Print address on #GP Jann Horn
2019-12-11 17:06 ` Borislav Petkov
2019-12-11 17:22 ` Andy Lutomirski
2019-12-11 17:29 ` Borislav Petkov
2019-12-11 18:17 ` Andy Lutomirski
2019-12-19 11:29 ` Borislav Petkov
2019-12-18 21:55 ` Jann Horn
2019-12-09 14:31 ` [PATCH v6 3/4] x86/dumpstack: Split out header line printing from __die() Jann Horn
2019-12-09 14:31 ` [PATCH v6 4/4] x86/kasan: Print original address on #GP Jann Horn
2019-12-11 17:37 ` Borislav Petkov
2019-12-18 22:33 ` Jann Horn [this message]
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