2018-03-13 0:31 GMT+01:00 Alexandre Belloni
> On 13/03/2018 at 00:13:38 +0100, Stefano Manni wrote:
>> In preparation to enabling -Wvla, remove VLAs and replace them with
>> fixed-length arrays instead.
>> rtc-mcp795.c uses a variable-length array declaration to contain
>> the command to write the rtcc; this can be replaced by a fixed-
>> size array of length 2 (instruction, address) + 32 (data out),
>> assuming a maximum data length of 32 bytes before wrap up.
>> This was prompted by https://lkml.org/lkml/2018/3/7/621
>> Signed-off-by: Stefano Manni <stefano.ma...@gmail.com>
>> drivers/rtc/rtc-mcp795.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>> diff --git a/drivers/rtc/rtc-mcp795.c b/drivers/rtc/rtc-mcp795.c
>> index 77f21331ae21..a5f504e2364c 100644
>> --- a/drivers/rtc/rtc-mcp795.c
>> +++ b/drivers/rtc/rtc-mcp795.c
>> @@ -61,6 +61,9 @@
>> #define SEC_PER_DAY (24 * 60 * 60)
>> +/* Maximum length for data out in write operation to RTCC */
>> +#define MCP795_MAX_DATAOUT_LEN 32
> This is wrong, see https://marc.info/?l=linux-kernel&m=152046370320811&w=2
You sure that the right value to use is 255 + 2? mcp795_rtcc_write() just writes
into the RTCC that contains only 32 registers (table 4-1 of
datasheet). I assumed
32 as the maximum length of data to write before wrapping up (start
from reg 0x0).
Probably 32 is just a wrong assumption but why did you choose 255?
Another thing: don't we need also to check count against the array length?
if (count > MCP795_MAX_DATAOUT_LEN)