From: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
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Subject: Re: [PATCH v4 13/18] kasan: arm64: x86: Handle int3 for inline KASAN reports
Date: Mon, 18 Aug 2025 08:26:11 +0200 [thread overview]
Message-ID: <nuzda7g3l2e4qeqdh6m4bmhlux6ywnrrh4ktivldljm2od7vou@z4wtuggklxei> (raw)
In-Reply-To: <20250813151702.GO4067720@noisy.programming.kicks-ass.net>
On 2025-08-13 at 17:17:02 +0200, Peter Zijlstra wrote:
>On Tue, Aug 12, 2025 at 03:23:49PM +0200, Maciej Wieczor-Retman wrote:
>> Inline KASAN on x86 does tag mismatch reports by passing the faulty
>> address and metadata through the INT3 instruction - scheme that's setup
>> in the LLVM's compiler code (specifically HWAddressSanitizer.cpp).
>>
>> Add a kasan hook to the INT3 handling function.
>>
>> Disable KASAN in an INT3 core kernel selftest function since it can raise
>> a false tag mismatch report and potentially panic the kernel.
>>
>> Make part of that hook - which decides whether to die or recover from a
>> tag mismatch - arch independent to avoid duplicating a long comment on
>> both x86 and arm64 architectures.
>>
>> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
>
>Can we please split this into an arm64 and x86 patch. Also, why use int3
>here rather than a #UD trap, which we use for all other such cases?
Sure, two patches seem okay. I'll first add all the new functions and modify the
x86 code, then add the arm64 patch which will replace its die() + comment with
kasan_inline_recover().
About INT3 I'm not sure, it's just how it's written in the LLVM code. I didn't
see any justification why it's not #UD. My guess is SMD describes INT3 as an
interrupt for debugger purposes while #UD is described as "for software
testing". So from the documentation point INT3 seems to have a stronger case.
Does INT3 interfere with something? Or is #UD better just because of
consistency?
--
Kind regards
Maciej Wieczór-Retman
next prev parent reply other threads:[~2025-08-18 6:28 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-12 13:23 [PATCH v4 00/18] kasan: x86: arm64: KASAN tag-based mode for x86 Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 01/18] kasan: sw_tags: Use arithmetic shift for shadow computation Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 02/18] kasan: sw_tags: Support tag widths less than 8 bits Maciej Wieczor-Retman
2025-08-13 14:48 ` Ada Couprie Diaz
2025-08-18 4:24 ` Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 03/18] kasan: Fix inline mode for x86 tag-based mode Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 04/18] x86: Add arch specific kasan functions Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 05/18] kasan: arm64: x86: Make special tags arch specific Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 06/18] x86: Reset tag for virtual to physical address conversions Maciej Wieczor-Retman
2025-08-14 7:15 ` Mike Rapoport
2025-08-18 5:29 ` Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 07/18] mm: x86: Untag addresses in EXECMEM_ROX related pointer arithmetic Maciej Wieczor-Retman
2025-08-14 7:26 ` Mike Rapoport
2025-08-18 5:47 ` Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 08/18] x86: Physical address comparisons in fill_p*d/pte Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 09/18] x86: KASAN raw shadow memory PTE init Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 10/18] x86: LAM compatible non-canonical definition Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 11/18] x86: LAM initialization Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 12/18] x86: Minimal SLAB alignment Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 13/18] kasan: arm64: x86: Handle int3 for inline KASAN reports Maciej Wieczor-Retman
2025-08-13 14:49 ` Ada Couprie Diaz
2025-08-18 5:57 ` Maciej Wieczor-Retman
2025-08-13 15:17 ` Peter Zijlstra
2025-08-18 6:26 ` Maciej Wieczor-Retman [this message]
2025-09-08 15:40 ` Peter Zijlstra
2025-09-09 8:47 ` Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 14/18] kasan: x86: Apply multishot to the inline report handler Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 15/18] kasan: x86: Logical bit shift for kasan_mem_to_shadow Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 16/18] mm: Unpoison pcpu chunks with base address tag Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 17/18] mm: Unpoison vms[area] addresses with a common tag Maciej Wieczor-Retman
2025-08-12 13:23 ` [PATCH v4 18/18] x86: Make software tag-based kasan available Maciej Wieczor-Retman
2025-08-13 8:16 ` [PATCH v4 00/18] kasan: x86: arm64: KASAN tag-based mode for x86 Kiryl Shutsemau
2025-08-13 10:39 ` Maciej Wieczor-Retman
2025-08-13 11:05 ` Kiryl Shutsemau
2025-08-13 11:44 ` Maciej Wieczor-Retman
2025-08-21 12:30 ` Ada Couprie Diaz
2025-08-22 7:36 ` Maciej Wieczor-Retman
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