Den 21.08.2019 09.24, skrev Dan Carpenter:
> This code will likely crash if we try to do a zero byte write. The code
> looks like this:
>
> /* strip trailing whitespace */
> for (i = count - 1; i > 0; i--)
> if (isspace(buf[i]))
> ...
>
> We're writing zero bytes so count = 0. You would think that "count - 1"
> would be negative one, but because "i" is unsigned it is a large
> positive numer instead. The "i > 0" condition is true and the "buf[i]"
> access will be out of bounds.
>
> The fix is to make "i" signed and now everything works as expected. The
> upper bound of "count" is capped in __kernel_write() at MAX_RW_COUNT so
> we don't have to worry about it being higher than INT_MAX.
>
> Fixes: 02dd95fe3169 ("drm/tinydrm: Add MIPI DBI support")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
Thanks Dan, applied to drm-misc-next with adjusted title:
-drm/tinydrm: fix a loop in debugfs code
+drm/mipi-dbi: fix a loop in debugfs code
Noralf.
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