On Mon, 15 Nov 2021, Marijn Suijten wrote:
When not specifying num-strings in the DT the default is used, but +1 is added to it which turns WLED3 into 4 and WLED4/5 into 5 strings instead of 3 and 4 respectively, causing out-of-bounds reads and register read/writes. This +1 exists for a deficiency in the DT parsing code, and is simply omitted entirely - solving this oob issue - by parsing the property separately much like qcom,enabled-strings.
This also enables more stringent checks on the maximum value when qcom,enabled-strings is provided in the DT, by parsing num-strings after enabled-strings to allow it to check against (and in a subsequent patch override) the length of enabled-strings: it is invalid to set num-strings higher than that. The DT currently utilizes it to get around an incorrect fixed read of four elements from that array (has been addressed in a prior patch) by setting a lower num-strings where desired.
Fixes: 93c64f1ea1e8 ("leds: add Qualcomm PM8941 WLED driver") Signed-off-by: Marijn Suijten marijn.suijten@somainline.org Reviewed-By: AngeloGioacchino Del Regno angelogioacchino.delregno@somainline.org
drivers/video/backlight/qcom-wled.c | 48 ++++++++++------------------- 1 file changed, 16 insertions(+), 32 deletions(-)
Applied, thanks.