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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id w2sm10588697pjq.5.2021.08.22.00.56.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Aug 2021 00:56:55 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Nikolay Borisov , David Sterba , Rasmus Villemoes , Daniel Micay , Francis Laniel , Bart Van Assche , David Gow , linux-mm@kvack.org, clang-built-linux@googlegroups.com, linux-hardening@vger.kernel.org Subject: [PATCH for-next 25/25] btrfs: Use memset_startat() to clear end of struct Date: Sun, 22 Aug 2021 00:51:22 -0700 Message-Id: <20210822075122.864511-26-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210822075122.864511-1-keescook@chromium.org> References: <20210822075122.864511-1-keescook@chromium.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1155; h=from:subject; bh=XHjqu1RreJZUS0lhfMO2nlVUCup75rB1cNpejDSomCQ=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhIgH6ZxQKCftHw+bbIsZDc7/cNC2VaaPC/Bzvi8PJ jBI2gduJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYSIB+gAKCRCJcvTf3G3AJlX6D/ 0ccDotcFu1yUXFehzHwNXSmCdP2dRq6MGepK0y703lxGRgYRXH8mgO0Xcee95Lf1qk9czxzNowS6Go sS7b4Pkw/E9zlTldMaPdOl2QcI5czJx7DD1K4TcjXVJIFmS6pKUwT+eyjq0GxpYr7UP56JMbPUEqe5 /FFM82ogo5GKXC7ZpnDH0SAN0vm6d6FA+qTuz09iEWwG/fISmVDLNgt5/5XHX+FBNT9x7tglj+UGJo J1LFFMUYLrtM2xP6W7KZ2dSwVZJXgKwar1gnOJNrESpF5p0R3pv662l39w1R5CaPsMt7yCRg/dKY83 xPpJ6QS6fappboPIqlmH5DsKrwK5tkqUZOo965oL22gXqQLlJrDFBpS+HcA90K77tmUDHw0cA1oZCj xEMwTwSaEaYhTUAETc8W+rxxhHOoWltHARk5AyjoMLUAB9R97PZJqtlzmw3T+LCpHan7/53N3wtmDo twQpqQVoR6GDsE+DDBy0ofV2si8wOgHKYzXDMIJhJ35Axs/8MT4SZe+NZy84FF+nL8DpWAWNa/4QPj +lqLt0IFYNIrpylbCHV7Fr8Rw7AwdoPxNmNyLThTwo3dPw1G+ZNgvqLhqFDYZIQiBRh8ruca3dYIvv JSKCxSme2hIV5U+VcQHoQKeTVwGooGQAZsYFH1gkRt9Apq6nbH2JORDnJ6kQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields. Use memset_startat() so memset() doesn't get confused about writing beyond the destination member that is intended to be the starting point of zeroing through the end of the struct. Reviewed-by: Nikolay Borisov Acked-by: David Sterba Signed-off-by: Kees Cook --- fs/btrfs/root-tree.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c index 702dc5441f03..12ceb14a1141 100644 --- a/fs/btrfs/root-tree.c +++ b/fs/btrfs/root-tree.c @@ -39,10 +39,8 @@ static void btrfs_read_root_item(struct extent_buffer *eb, int slot, need_reset = 1; } if (need_reset) { - memset(&item->generation_v2, 0, - sizeof(*item) - offsetof(struct btrfs_root_item, - generation_v2)); - + /* Clear all members from generation_v2 onwards. */ + memset_startat(item, 0, generation_v2); generate_random_guid(item->uuid); } } -- 2.30.2