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Sat, 29 Nov 2025 17:24:28 +0800 (CST) Received: from kwepemj100009.china.huawei.com (unknown [7.202.194.3]) by mail.maildlp.com (Postfix) with ESMTPS id 22071180B3F; Sat, 29 Nov 2025 17:26:19 +0800 (CST) Received: from DESKTOP-A37P9LK.huawei.com (10.67.109.17) by kwepemj100009.china.huawei.com (7.202.194.3) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 29 Nov 2025 17:26:18 +0800 From: Xie Yuanbin To: , , , , CC: , , , , , , , , , , , , , , , Subject: Re: [Bug report] hash_name() may cross page boundary and trigger Date: Sat, 29 Nov 2025 17:25:45 +0800 Message-ID: <20251129092545.5181-1-xieyuanbin1@huawei.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251129090813.GK3538@ZenIV> References: <20251129090813.GK3538@ZenIV> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.67.109.17] X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemj100009.china.huawei.com (7.202.194.3) X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 223B34000D X-Stat-Signature: 7fiztgkjp9rezwpqw4jw1k9z4pjz9uat X-HE-Tag: 1764408383-110533 X-HE-Meta: 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 M8Sbo02U zsYFEjxJTnqAz2YN16HETp4NaPuBJ8N7t/cYI/cGhc5A08HsC7XJSNByobMZb6J/X8vRB5ullfN+AdHjFvyunJ9K75tCfYXnNUqgcuc32Wpv0GQCXCIQLFGjaIdpidcmG9WjNaDmZPvs1mReyn9Q89a5rVIxwfgfwuCpE2CIKgzwFfOQUX3cdviIUKuLyytnPeAdF+qTuBnUwsRh5cA63lqXg7EfRQK5jiAo+PBQFL0YBYQWmrCfEem+iBreWRzuFmWWlxnALTeBVdgzafH9cXgegeylknV0DZEvtLjx8CY56ELThiruRE8thdL9ZmgMMCrL39LjV9V+wf5avQc7SvkEotBXNyvnQqW4OasXvHAfU2Q34chj3s/wIzD0JqYaLKl2ZhmeMig8gmo3RpTjWYN+RL7zmbBduBSvmeljJ07Anj5mLTPtXZ4oZzg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 29 Nov 2025 09:08:13 +0000, Al Viro wrote: > On Sat, Nov 29, 2025 at 12:08:17PM +0800, Xie Yuanbin wrote: > >> I think the `user_mode(regs)` check is necessary because the label >> no_context actually jumps to __do_kernel_fault(), whereas page fault >> from user mode should jump to `__do_user_fault()`. >> >> Alternatively, we would need to change `goto no_context` to >> `goto bad_area`. Or perhaps I misunderstood something, please point it out. > > FWIW, goto bad_area has an obvious problem: uses of 'fault' value, which > contains garbage. Yes, I know it, I just omitted it. Thank you for pointing that out. > or > if (unlikely(addr >= TASK_SIZE)) { > fault = 0; > code = SEGV_MAPERR; > goto bad_area; > } In fact, I have already submitted another patch, which is exactly the way as you described: Link: https://lore.kernel.org/20251127140109.191657-1-xieyuanbin1@huawei.com The only difference is that I will move the judgment to before local_irq_enable(). The reason for doing this is to fix another bug, you can find more details about it here: Link: https://lore.kernel.org/20250925025744.6807-1-xieyuanbin1@huawei.com Link: https://lore.kernel.org/20251129021815.9679-1-xieyuanbin1@huawei.com To keep the email concise, I will not repeat the description here. Xie Yuanbin