From: "Luck, Tony" <tony.luck@intel.com>
To: Borislav Petkov <bp@alien8.de>, Shuai Xue <xueshuai@linux.alibaba.com>
Cc: "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 22:05:12 +0000 [thread overview]
Message-ID: <SJ1PR11MB6083654405F2721E5AA0C1F2FCD52@SJ1PR11MB6083.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20250307204018.GAZ8tZstt11Y4KFprC@fat_crate.local>
> The more important part which I asked for already is, is is_copy_from_user()
> exhaustive in determining the that the operation really is a copy from user?
>
> The EX_TYPE_UACCESS things *explicitly* marked such places in the code. Does
> is_copy_from_user() guarantee the same, without false positives?
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.
So no false positives.
There could be some false negatives if some other instruction is doing
the "load" operation.
-Tony
next prev parent reply other threads:[~2025-03-07 22:05 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 [this message]
2025-03-07 22:46 ` Borislav Petkov
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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