6.8-stable review patch. If anyone has any objections, please let me know.
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From: Kent Gibson warthog618@gmail.com
[ Upstream commit ee0166b637a5e376118e9659e5b4148080f1d27e ]
If a line is requested with debounce, and that results in debouncing in software, and the line is subsequently reconfigured to enable edge detection then the allocation of the kfifo to contain edge events is overlooked. This results in events being written to and read from an uninitialised kfifo. Read events are returned to userspace.
Initialise the kfifo in the case where the software debounce is already active.
Fixes: 65cff7046406 ("gpiolib: cdev: support setting debounce") Signed-off-by: Kent Gibson warthog618@gmail.com Link: https://lore.kernel.org/r/20240510065342.36191-1-warthog618@gmail.com Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpio/gpiolib-cdev.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index 0b94c398c0649..5cca9e8803495 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -1199,6 +1199,8 @@ static int edge_detector_update(struct line *line, struct gpio_v2_line_config *lc, unsigned int line_idx, u64 edflags) { + u64 eflags; + int ret; u64 active_edflags = READ_ONCE(line->edflags); unsigned int debounce_period_us = gpio_v2_line_config_debounce_period(lc, line_idx); @@ -1210,6 +1212,18 @@ static int edge_detector_update(struct line *line, /* sw debounced and still will be...*/ if (debounce_period_us && READ_ONCE(line->sw_debounced)) { line_set_debounce_period(line, debounce_period_us); + /* + * ensure event fifo is initialised if edge detection + * is now enabled. + */ + eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS; + if (eflags && !kfifo_initialized(&line->req->events)) { + ret = kfifo_alloc(&line->req->events, + line->req->event_buffer_size, + GFP_KERNEL); + if (ret) + return ret; + } return 0; }