On Thu, Aug 26, 2021 at 08:24:52AM +0200, Marc Kleine-Budde wrote:

On 25.08.2021 22:04:55, Kees Cook wrote:

quoted

In support of enabling -Warray-bounds and -Wzero-length-bounds and
correctly handling run-time memcpy() bounds checking, replace all
open-coded flexible arrays (i.e. 0-element arrays) in unions with the
flex_array() helper macro.

This fixes warnings such as:

fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree':
fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds]
  209 |    anode->btree.u.internal[0].down = cpu_to_le32(a);
      |    ~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from fs/hpfs/hpfs_fn.h:26,
                 from fs/hpfs/anode.c:10:
fs/hpfs/hpfs.h:412:32: note: while referencing 'internal'
  412 |     struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving
      |                                ^~~~~~~~

drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg':
drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds]
  360 |  tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len];
      |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22,
                 from drivers/net/can/usb/etas_es58x/es58x_fd.c:17:
drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg'
  231 |   u8 raw_msg[0];
      |      ^~~~~~~

Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ayush Sawal <ayush.sawal@chelsio.com>
Cc: Vinay Kumar Yadav <redacted>
Cc: Rohit Maheshwari <redacted>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Kalle Valo <redacted>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Stanislaw Gruszka <stf_xl@wp.pl>
Cc: Luca Coelho <redacted>
Cc: "James E.J. Bottomley" <redacted>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <redacted>
Cc: Song Liu <redacted>
Cc: Yonghong Song <redacted>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Johannes Berg <redacted>
Cc: Mordechay Goodstein <redacted>
Cc: Lee Jones <redacted>
Cc: Wolfgang Grandegger <redacted>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Arunachalam Santhanam <redacted>
Cc: Vincent Mailhol <redacted>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: linux-crypto@vger.kernel.org
Cc: ath10k@lists.infradead.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linux-can@vger.kernel.org
Cc: bpf@vger.kernel.org
Signed-off-by: Kees Cook <redacted>
---
 drivers/net/can/usb/etas_es58x/es581_4.h          |  2 +-
 drivers/net/can/usb/etas_es58x/es58x_fd.h         |  2 +-

For the can drivers:

Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>

Thanks!

BTW: Is there opportunity for conversion, too?

| drivers/net/can/peak_canfd/peak_pciefd_main.c:146:32: warning: array of flexible structures

Oh, hrmpf. This isn't a sane use of flex arrays:


struct __packed pucan_rx_msg {
	...
	__le32	can_id;
	u8	d[];
};

struct pciefd_rx_dma {
        __le32 irq_status;
        __le32 sys_time_low;
        __le32 sys_time_high;
        struct pucan_rx_msg msg[];
} __packed __aligned(4);

I think that needs to be handled separately. How are you building to get
that warning, by the way? I haven't seen that in my builds...

-- 
Kees Cook