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Thu, 10 Apr 2025 03:57:30 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (unknown [10.72.112.38]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A03EF19560AD; Thu, 10 Apr 2025 03:57:26 +0000 (UTC) From: Baoquan He To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, david@redhat.com, osalvador@suse.de, yanjun.zhu@linux.dev, linux-kernel@vger.kernel.org, Baoquan He Subject: [PATCH v4 1/4] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() Date: Thu, 10 Apr 2025 11:57:14 +0800 Message-ID: <20250410035717.473207-2-bhe@redhat.com> In-Reply-To: <20250410035717.473207-1-bhe@redhat.com> References: <20250410035717.473207-1-bhe@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7C92F18000C X-Stat-Signature: ynw3p7z8yea3yzrig94etwbqzmbj6azs X-Rspam-User: X-HE-Tag: 1744257454-233024 X-HE-Meta: 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 OiYQ18lp hjBFNb1YGSB9xSYA++n0Oc5XPouAqSjxbHQXD4lEYdnBJsu39xAmp1lbCDfaE2lsQ+OtoiftWCermikJJdLpDr70VK9wBdUx5Cm8I4p3cJrpwQ/ByovKwNVNN+ZgQfM7pLzF747oHVpucEEkjcvObY5+WAuk0N/2RjafqflGcbxD5BU81GvwOs7ucbNkZsYDG3J01inGAmlZWOpq9YNzl336cMfaCuAIBeXQ7rZwesGHjYhBFSYIrk9fygOzzHcoWrPs3lLiBUqzvi7g1hhoyOnyN6JvkujjLx4IIDrLJomj8enhiQmzD4nePLXkE5QaPgkI/po7GsqG0CWVPxub7xCQQ5Lo8PyNzXXcJ5S0J/TQWXiTlfX7zcKgiLWoHuECEE4QJ 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: Not like fault_in_readable() or fault_in_writeable(), in fault_in_safe_writeable() local variable 'start' is increased page by page to loop till the whole address range is handled. However, it mistakenly calcalates the size of handled range with 'uaddr - start'. Fix it here. Signed-off-by: Baoquan He Fixes: fe673d3f5bf1 ("mm: gup: make fault_in_safe_writeable() use fixup_user_fault()") Reviewed-by: Oscar Salvador Acked-by: David Hildenbrand --- mm/gup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 92351e2fa876..84461d384ae2 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2207,8 +2207,8 @@ size_t fault_in_safe_writeable(const char __user *uaddr, size_t size) } while (start != end); mmap_read_unlock(mm); - if (size > (unsigned long)uaddr - start) - return size - ((unsigned long)uaddr - start); + if (size > start - (unsigned long)uaddr) + return size - (start - (unsigned long)uaddr); return 0; } EXPORT_SYMBOL(fault_in_safe_writeable);