From: Kent Gibson warthog618@gmail.com

mainline inclusion from mainline-v6.9 commit ee0166b637a5e376118e9659e5b4148080f1d27e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9U7YV CVE: CVE-2024-36898

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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

Conflicts: drivers/gpio/gpiolib-cdev.c [The original patch defines eflags instead of errflags, but eflags is already a parameter of the function, so rename to errflags.] Signed-off-by: Luo Gengkun luogengkun2@huawei.com --- 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 381cfa26a4a1..0f98a07efcd6 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -816,6 +816,8 @@ static int edge_detector_update(struct line *line, unsigned int line_idx, u64 eflags, bool polarity_change) { + u64 errflags; + int ret; unsigned int debounce_period_us = gpio_v2_line_config_debounce_period(lc, line_idx);

@@ -827,6 +829,18 @@ static int edge_detector_update(struct line *line, if (debounce_period_us && READ_ONCE(line->sw_debounced)) { line->eflags = eflags; WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us); + /* + * ensure event fifo is initialised if edge detection + * is now enabled. + */ + errflags = eflags & GPIO_V2_LINE_EDGE_FLAGS; + if (errflags && !kfifo_initialized(&line->req->events)) { + ret = kfifo_alloc(&line->req->events, + line->req->event_buffer_size, + GFP_KERNEL); + if (ret) + return ret; + } return 0; }