Re: [PATCH v2 2/5] treewide: Replace open-coded flex arrays in unions

[Marc Kleine-Budde]

On 25.08.2021 22:04:55, Kees Cook wrote:
> 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@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Ayush Sawal <ayush.sawal@xxxxxxxxxxx>
> Cc: Vinay Kumar Yadav <vinay.yadav@xxxxxxxxxxx>
> Cc: Rohit Maheshwari <rohitm@xxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> Cc: Stanislaw Gruszka <stf_xl@xxxxx>
> Cc: Luca Coelho <luciano.coelho@xxxxxxxxx>
> Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxx>
> Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Cc: Martin KaFai Lau <kafai@xxxxxx>
> Cc: Song Liu <songliubraving@xxxxxx>
> Cc: Yonghong Song <yhs@xxxxxx>
> Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> Cc: KP Singh <kpsingh@xxxxxxxxxx>
> Cc: Johannes Berg <johannes.berg@xxxxxxxxx>
> Cc: Mordechay Goodstein <mordechay.goodstein@xxxxxxxxx>
> Cc: Lee Jones <lee.jones@xxxxxxxxxx>
> Cc: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
> Cc: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
> Cc: Arunachalam Santhanam <arunachalam.santhanam@xxxxxxxxxxxx>
> Cc: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
> Cc: Mikulas Patocka <mikulas@xxxxxxxxxxxxxxxxxxxxxxxx>
> Cc: linux-crypto@xxxxxxxxxxxxxxx
> Cc: ath10k@xxxxxxxxxxxxxxxxxxx
> Cc: linux-wireless@xxxxxxxxxxxxxxx
> Cc: netdev@xxxxxxxxxxxxxxx
> Cc: linux-scsi@xxxxxxxxxxxxxxx
> Cc: linux-can@xxxxxxxxxxxxxxx
> Cc: bpf@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxxx>

BTW: Is there opportunity for conversion, too?

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

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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