linux-kernel - [PATCH 4.4 82/93] gpio: pcf857x: Fix missing first interrupt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210301161010.908180451@linuxfoundation.org>
Date:   Mon,  1 Mar 2021 17:13:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxim Kiselev <bigunclemax@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH 4.4 82/93] gpio: pcf857x: Fix missing first interrupt

From: Maxim Kiselev <bigunclemax@...il.com>

commit a8002a35935aaefcd6a42ad3289f62bab947f2ca upstream.

If no n_latch value will be provided at driver probe then all pins will
be used as an input:

    gpio->out = ~n_latch;

In that case initial state for all pins is "one":

    gpio->status = gpio->out;

So if pcf857x IRQ happens with change pin value from "zero" to "one"
then we miss it, because of "one" from IRQ and "one" from initial state
leaves corresponding pin unchanged:
change = (gpio->status ^ status) & gpio->irq_enabled;

The right solution will be to read actual state at driver probe.

Cc: stable@...r.kernel.org
Fixes: 6e20a0a429bd ("gpio: pcf857x: enable gpio_to_irq() support")
Signed-off-by: Maxim Kiselev <bigunclemax@...il.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpio/gpio-pcf857x.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpio/gpio-pcf857x.c
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -370,7 +370,7 @@ static int pcf857x_probe(struct i2c_clie
 	 * reset state.  Otherwise it flags pins to be driven low.
 	 */
 	gpio->out = ~n_latch;
-	gpio->status = gpio->out;
+	gpio->status = gpio->read(gpio->client);
 
 	status = gpiochip_add(&gpio->chip);
 	if (status < 0)