On 2021-10-05 10:19:47, Daniel Thompson wrote:
On Mon, Oct 04, 2021 at 09:27:36PM +0200, 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 allowing one extra iteration of the wled_var_cfg function parsing this particular property.
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 | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c index 27e8949c7922..66ce77ee3099 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -1255,17 +1255,17 @@ static const struct wled_var_cfg wled5_ovp_cfg = {
static u32 wled3_num_strings_values_fn(u32 idx) {
- return idx + 1;
- return idx;
}
static const struct wled_var_cfg wled3_num_strings_cfg = { .fn = wled3_num_strings_values_fn,
- .size = 3,
- .size = 4, /* [0, 3] */
0 is not a valid value for this property.
These comments represent the possible loop iterations the DT "cfg parser" runs through, starting at j=0 and running up until and including j=3. Should I make that more clear or omit these comments entirely?
- Marijn
};
static const struct wled_var_cfg wled4_num_strings_cfg = { .fn = wled3_num_strings_values_fn,
- .size = 4,
- .size = 5, /* [0, 4] */
Ditto.
};
static u32 wled3_switch_freq_values_fn(u32 idx) @@ -1520,8 +1520,6 @@ static int wled_configure(struct wled *wled) *bool_opts[i].val_ptr = true; }
- cfg->num_strings = cfg->num_strings + 1;
- string_len = of_property_count_elems_of_size(dev->of_node, "qcom,enabled-strings", sizeof(u32));
-- 2.33.0