[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20240527115419.92606-2-warthog618@gmail.com>
Date: Mon, 27 May 2024 19:54:17 +0800
From: Kent Gibson <warthog618@...il.com>
To: linux-kernel@...r.kernel.org,
linux-gpio@...r.kernel.org,
brgl@...ev.pl,
linus.walleij@...aro.org
Cc: Kent Gibson <warthog618@...il.com>
Subject: [PATCH 1/3] gpiolib: cdev: Add INIT_KFIFO() for linereq events
The initialisation of the linereq events kfifo relies on the struct being
zeroed and a subsequent call to kfifo_alloc(). The call to kfifo_alloc()
is deferred until edge detection is first enabled for the linereq. If the
kfifo is inadvertently accessed before the call to kfifo_alloc(), as was
the case in a recently discovered bug, it behaves as a FIFO of size 1 with
an element size of 0, so writes and reads to the kfifo appear successful
but copy no actual data.
As a defensive measure, initialise the kfifo with INIT_KFIFO() when the
events kfifo is constructed. This initialises the kfifo element size
and zeroes its data pointer, so any inadvertant access prior to the
kfifo_alloc() call will trigger an oops.
Signed-off-by: Kent Gibson <warthog618@...il.com>
---
drivers/gpio/gpiolib-cdev.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 9dad67ea2597..d4e47960cc98 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1774,6 +1774,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
mutex_init(&lr->config_mutex);
init_waitqueue_head(&lr->wait);
+ INIT_KFIFO(lr->events);
lr->event_buffer_size = ulr.event_buffer_size;
if (lr->event_buffer_size == 0)
lr->event_buffer_size = ulr.num_lines * 16;
--
2.39.2
Powered by blists - more mailing lists