Messages in this thread | | | Date | Tue, 24 Apr 2018 06:43:15 +0100 | From | Lee Jones <> | Subject | Re: [PATCH] rave-sp: Remove VLA |
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On Mon, 23 Apr 2018, Kyle Spiers wrote:
> As part of the effort to remove VLAs from the kernel[1], this creates > constants for the checksum lengths of CCITT and 8B2C and changes > crc_calculated to be the maximum size of a checksum. > > https://lkml.org/lkml/2018/3/7/621 > > Signed-off-by: Kyle Spiers <ksspiers@google.com> > --- > drivers/mfd/rave-sp.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/mfd/rave-sp.c b/drivers/mfd/rave-sp.c > index 5c858e784a89..99fa482419f9 100644 > --- a/drivers/mfd/rave-sp.c > +++ b/drivers/mfd/rave-sp.c > @@ -45,7 +45,9 @@ > #define RAVE_SP_DLE 0x10 > > #define RAVE_SP_MAX_DATA_SIZE 64 > -#define RAVE_SP_CHECKSUM_SIZE 2 /* Worst case scenario on RDU2 */ > +#define RAVE_SP_CHECKSUM_8B2C 1 > +#define RAVE_SP_CHECKSUM_CCITT 2 > +#define RAVE_SP_CHECKSUM_SIZE RAVE_SP_CHECKSUM_CCITT > /* > * We don't store STX, ETX and unescaped bytes, so Rx is only > * DATA + CSUM > @@ -415,7 +417,12 @@ static void rave_sp_receive_frame(struct rave_sp *sp, > const size_t payload_length = length - checksum_length; > const u8 *crc_reported = &data[payload_length]; > struct device *dev = &sp->serdev->dev; > - u8 crc_calculated[checksum_length]; > + u8 crc_calculated[RAVE_SP_CHECKSUM_SIZE]; > + > + if (unlikely(length > sizeof(crc_calculated))) {
Forgive me if I have this wrong (it's still very early here), but this doesn't leave any room for the payload?
<-- length --> <ck len><- payload length -> [CK][CK][D][A][T][A] .. [64]
It is my hope that length would always be larger than the size of the checksum, or else there would never be any data?
Should this not be:
if (unlikely(length > RAVE_SP_MAX_DATA_SIZE))
Nit: Adding the check is also an unrelated change, so would require a separate patch.
> + dev_warn(dev, "Dropping oversized frame\n"); > + return; > + } > > print_hex_dump(KERN_DEBUG, "rave-sp rx: ", DUMP_PREFIX_NONE, > 16, 1, data, length, false);
-- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
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