Re: [PATCH] staging: fbtft: fix unaligned access and txbuf safety issues

[Dan Carpenter]

On Thu, Jun 25, 2026 at 07:42:15PM +0800, suryasaimadhu wrote:
> This patch addresses several pre-existing issues in the fbtft driver:
> 
> 1. define_fbtft_write_reg(): when par->startbyte is set, buf is
>    advanced by one byte creating a misaligned pointer for 16-bit types.
>    Use put_unaligned() for register writes and fix the SPI transfer
>    size from len * (sizeof(data_type) + offset) to
>    len * sizeof(data_type) + offset.
> 
> 2. fbtft_write_vmem16_bus8() and fb_ra8875 write_vmem16_bus8(): same
>    unaligned 16-bit stores when txbuf is byte-offset for a start
>    prefix. Use put_unaligned() for pixel data copies.
> 
> 3. tx_array_size underflow: both vmem helpers subtract 2 from
>    tx_array_size when a startbyte prefix is used. A small txbuflen
>    device property causes unsigned underflow and out-of-bounds heap
>    writes. Fall back to the non-buffered write path when the buffer
>    is too small.
> 
> 4. fb_ra8875 write_vmem16_bus8(): missing NULL check for
>    par->txbuf.buf, which remains NULL on big-endian when txbuflen is
>    0 because the PAGE_SIZE fallback is little-endian only. Fall back
>    to direct write when the buffer is missing.
> 
> Also replace empty modifier arguments in define_fbtft_write_reg() with
> a no-op macro to fix checkpatch warnings.
> 
> Signed-off-by: suryasaimadhu <suryasaimadhu369@xxxxxxxxx>

Is this how you would sign a legal document?

This patch does too many things at once.  Split it up.  Also please
a delay between sending us patches.  Otherwise it's overwhelming to
deal with.  Bunch them together in a patchset instead of sending them
one by one.

regards,
dan carpenter