From: Kees Cook <keescook@chromium.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jann Horn <jannh@google.com>, Kees Cook <kees@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux LLVM <llvm@lists.linux.dev>,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: CONFIG_UBSAN_TRAP #UD error message on x86 [was: Re: [CRASH][BISECTED] 6.4.1 crash in boot]
Date: Wed, 5 Jul 2023 14:54:01 -0700 [thread overview]
Message-ID: <202307051453.007A5ED7@keescook> (raw)
In-Reply-To: <20230705213113.GC2813335@hirez.programming.kicks-ass.net>
On Wed, Jul 05, 2023 at 11:31:13PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 05, 2023 at 02:08:09PM -0700, Kees Cook wrote:
>
> > > Even just a "WARNING: CONFIG_UBSAN_TRAP active, #UD might be caused by
> > > that" on every #UD that does not come from a known BUG() location or
> > > such might be better than nothing...
> >
> > I've considered it, but usually CONFIG_UBSAN_TRAP isn't accidentally
> > set. Also, the crash info is something we can get help from on the
> > compiler side, to mark up where the traps are, similar to what we do
> > with KCFI, but it hasn't happened yet for x86. For example, arm64
> > already encodes the details in the trap instruction itself:
> > https://git.kernel.org/linus/25b84002afb9dc9a91a7ea67166879c13ad82422
>
> Right, so you could easily use a different #UD instruction that has an
> immediate, something like:
>
> 0f b9 40 ff ud1 -0x1(%rax),%rax
Ah yeah, that would be easier, probably. It could match what arm64 does.
--
Kees Cook
next prev parent reply other threads:[~2023-07-05 21:54 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-02 16:36 [CRASH][BISECTED] 6.4.1 crash in boot Mirsad Goran Todorovac
2023-07-03 1:44 ` Bagas Sanjaya
2023-07-03 3:20 ` Kees Cook
2023-07-03 3:26 ` Guenter Roeck
2023-07-03 3:53 ` Mirsad Goran Todorovac
2023-07-03 4:30 ` Kees Cook
2023-07-03 4:38 ` Guenter Roeck
2023-07-03 4:53 ` Kees Cook
2023-07-03 4:50 ` Mirsad Goran Todorovac
2023-07-03 3:58 ` Guenter Roeck
2023-07-03 5:18 ` Mirsad Goran Todorovac
2023-07-03 5:18 ` Mirsad Goran Todorovac
2023-07-03 5:41 ` Kees Cook
2023-07-03 7:03 ` Mirsad Goran Todorovac
2023-07-03 19:03 ` Kees Cook
2023-07-03 23:09 ` Kees Cook
2023-07-04 17:20 ` Mirsad Todorovac
2023-07-04 21:36 ` Kees Cook
2023-07-04 23:15 ` Mirsad Todorovac
2023-07-05 2:09 ` Kees Cook
2023-07-05 5:18 ` Mirsad Todorovac
2023-07-05 15:16 ` CONFIG_UBSAN_TRAP #UD error message on x86 [was: Re: [CRASH][BISECTED] 6.4.1 crash in boot] Jann Horn
2023-07-05 21:08 ` Kees Cook
2023-07-05 21:31 ` Peter Zijlstra
2023-07-05 21:54 ` Kees Cook [this message]
2023-07-06 5:02 ` [CRASH][BISECTED] 6.4.1 crash in boot Mirsad Todorovac
2023-07-03 3:40 ` Mirsad Goran Todorovac
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