From mboxrd@z Thu Jan 1 00:00:00 1970 From: andreyknvl@google.com (Andrey Konovalov) Date: Thu, 30 Aug 2018 13:41:12 +0200 Subject: [PATCH v6 07/11] fs, arm64: untag user address in copy_mount_options In-Reply-To: References: Message-ID: <89806bc1c1f85fa97c62887075cc2d46b8bdeee2.1535629099.git.andreyknvl@google.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org In copy_mount_options a user address is being subtracted from TASK_SIZE. If the address is lower than TASK_SIZE, the size is calculated to not allow the exact_copy_from_user() call to cross TASK_SIZE boundary. However if the address is tagged, then the size will be calculated incorrectly. Untag the address before subtracting. Signed-off-by: Andrey Konovalov --- fs/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index 99186556f8d3..51f763fb9430 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2672,7 +2672,7 @@ void *copy_mount_options(const void __user * data) * the remainder of the page. */ /* copy_from_user cannot cross TASK_SIZE ! */ - size = TASK_SIZE - (unsigned long)data; + size = TASK_SIZE - (unsigned long)untagged_addr(data); if (size > PAGE_SIZE) size = PAGE_SIZE; -- 2.19.0.rc0.228.g281dcd1b4d0-goog