From: Borislav Petkov <bp@alien8.de>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Shuai Xue <xueshuai@linux.alibaba.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"yazen.ghannam@amd.com" <yazen.ghannam@amd.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linmiaohe@huawei.com" <linmiaohe@huawei.com>,
"nao.horiguchi@gmail.com" <nao.horiguchi@gmail.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"jpoimboe@kernel.org" <jpoimboe@kernel.org>,
"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"baolin.wang@linux.alibaba.com" <baolin.wang@linux.alibaba.com>,
"tianruidong@linux.alibaba.com" <tianruidong@linux.alibaba.com>
Subject: Re: [PATCH v4 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context
Date: Fri, 7 Mar 2025 23:46:45 +0100 [thread overview]
Message-ID: <20250307224645.GKZ8t3VX5a5FhqNyZG@fat_crate.local> (raw)
In-Reply-To: <SJ1PR11MB6083654405F2721E5AA0C1F2FCD52@SJ1PR11MB6083.namprd11.prod.outlook.com>
On Fri, Mar 07, 2025 at 10:05:12PM +0000, Luck, Tony wrote:
> is_copy_from_user() decodes the instruction that took the trap. It looks for
> MOV, MOVZ and MOVS instructions to find the source address, and then
> checks whether that's user (< TASK_SIZE_MAX) or kernel.
You mean there's absolutely nothing else like, say, some epbf or some other
hackery we tend to do in the kernel (or we will do in the future) which won't
create the exact same two conditions:
- one of the three insns
- user mem read
and it would cause a recovery action.
Perhaps it still might be the proper thing to do even then but it does sound
fishy and unclean to me.
Nothing beats the explicit markup we had until recently...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2025-03-07 22:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-07 5:44 [PATCH v4 0/3] mm/hwpoison: Fix regressions in memory failure handling Shuai Xue
2025-03-07 5:44 ` [PATCH v4 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context Shuai Xue
2025-03-07 20:40 ` Borislav Petkov
2025-03-07 22:05 ` Luck, Tony
2025-03-07 22:46 ` Borislav Petkov [this message]
2025-03-07 23:11 ` Luck, Tony
2025-03-07 23:22 ` Borislav Petkov
2025-03-08 11:27 ` Shuai Xue
2025-03-08 11:25 ` Shuai Xue
2025-03-07 5:44 ` [PATCH v4 2/3] mm/hwpoison: Do not send SIGBUS to processes with recovered clean pages Shuai Xue
2025-03-12 6:39 ` Miaohe Lin
2025-03-12 8:03 ` Shuai Xue
2025-03-07 5:44 ` [PATCH v4 3/3] mm: memory-failure: Enhance comments for return value of memory_failure() Shuai Xue
2025-03-07 17:20 ` [PATCH v4 0/3] mm/hwpoison: Fix regressions in memory failure handling Luck, Tony
2025-03-08 11:36 ` Shuai Xue
2025-03-12 11:28 Shuai Xue
2025-03-12 11:28 ` [PATCH v4 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context Shuai Xue
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