On Thu, Feb 02, 2023 at 07:32:00PM -0600, Gustavo A. R. Silva wrote:
> One-element arrays are deprecated, and we are replacing them with flexible
> array members instead. So, replace one-element arrays with flexible-array
> members in multiple structures.
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [1].
>
> This results in no differences in binary output.
Sorry for blast from the past, but I have a question here.
This change seems converts many of the flexible arrays in this driver.
But what's behind this one?
struct host_cmd_ds_802_11_scan_ext {
u32 reserved;
u8 tlv_buffer[1];
} __packed;
AFAIU this needs also some care. On the real machine I have got this
elo 16 17:51:58 surfacebook kernel: ------------[ cut here ]------------
elo 16 17:51:58 surfacebook kernel: memcpy: detected field-spanning write (size 243) of single field "ext_scan->tlv_buffer" at drivers/net/wireless/marvell/mwifiex/scan.c:2239 (size 1)
elo 16 17:51:58 surfacebook kernel: WARNING: CPU: 0 PID: 498 at drivers/net/wireless/marvell/mwifiex/scan.c:2239 mwifiex_cmd_802_11_scan_ext+0x83/0x90 [mwifiex]
which leads to
memcpy(ext_scan->tlv_buffer, scan_cfg->tlv_buf, scan_cfg->tlv_buf_len);
but the code allocates 2k or more for the command buffer, so this seems
quite enough for 243 bytes.
--
With Best Regards,
Andy Shevchenko
