On Mon, May 01, 2023 at 06:01:19PM -0700, Dmitry Torokhov wrote:
> input_abs_set_val() can nominally call input_alloc_absinfo() which may
> allocate memory with GFP_KERNEL flag. This does not happen when
> input_abs_set_val() is called by the input core to set current MT slot when
> handling a new input event, but it trips certain static analyzers.
>
> Rearrange the code to access the relevant structures directly.
>
> Reported-by: Teng Qi <starmiku1207184332@xxxxxxxxx>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Reviewed-by: Peter Hutterer <peter.hutterer@xxxxxxxxx>
If git grep is to be believed, this is the only use of
input_abs_set_val. Maybe removing that function is an option?
Are there external drivers that rely on this (instead of sending an
event)?
Cheers,
Peter
> ---
> drivers/input/input.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index 37e876d45eb9..f791d14ecf23 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -190,6 +190,7 @@ static int input_handle_abs_event(struct input_dev *dev,
> unsigned int code, int *pval)
> {
> struct input_mt *mt = dev->mt;
> + bool is_new_slot = false;
> bool is_mt_event;
> int *pold;
>
> @@ -210,6 +211,7 @@ static int input_handle_abs_event(struct input_dev *dev,
> pold = &dev->absinfo[code].value;
> } else if (mt) {
> pold = &mt->slots[mt->slot].abs[code - ABS_MT_FIRST];
> + is_new_slot = mt->slot != dev->absinfo[ABS_MT_SLOT].value;
> } else {
> /*
> * Bypass filtering for multi-touch events when
> @@ -228,8 +230,8 @@ static int input_handle_abs_event(struct input_dev *dev,
> }
>
> /* Flush pending "slot" event */
> - if (is_mt_event && mt && mt->slot != input_abs_get_val(dev, ABS_MT_SLOT)) {
> - input_abs_set_val(dev, ABS_MT_SLOT, mt->slot);
> + if (is_new_slot) {
> + dev->absinfo[ABS_MT_SLOT].value = mt->slot;
> return INPUT_PASS_TO_HANDLERS | INPUT_SLOT;
> }
>
> --
> 2.40.1.495.gc816e09b53d-goog
>
>
> --
> Dmitry
