From: Lucas Stach <l.stach@pengutronix.de>
To: Oleksij Rempel <linux@rempel-privat.de>, barebox@lists.infradead.org
Subject: Re: [PATCH v1 2/9] pinctrl: tegra30: fix "Possible null pointer dereference: group" warning
Date: Wed, 21 Nov 2018 10:16:58 +0100 [thread overview]
Message-ID: <1542791818.23859.1.camel@pengutronix.de> (raw)
In-Reply-To: <20181120200714.3692-3-linux@rempel-privat.de>
Am Dienstag, den 20.11.2018, 21:07 +0100 schrieb Oleksij Rempel:
> The code is correct but it takes more seconds for me to understand.
> And static code analyzer do not understand it at all.
>
> > Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
> ---
> drivers/pinctrl/pinctrl-tegra30.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pinctrl/pinctrl-tegra30.c b/drivers/pinctrl/pinctrl-tegra30.c
> index d9b49c57d..ffb04eebb 100644
> --- a/drivers/pinctrl/pinctrl-tegra30.c
> +++ b/drivers/pinctrl/pinctrl-tegra30.c
> @@ -658,8 +658,8 @@ static int pinctrl_tegra30_set_drvstate(struct pinctrl_tegra30 *ctrl,
> > break;
> > }
> > }
> > - /* if no matching drivegroup is found */
> > - if (i == ctrl->drvdata->num_drvgrps)
> +
> > + if (!group)
> > return 0;
Huh? This is a pretty standard idiom in C codebases to check if we
broke out of a loop early.
Actually this change breaks the code, as this check is inside of an
outer loop that doesn't reinitialize the group variable. So while the
code as-is correctly checks if a group was found in the current
iteration of the outer loop, after this patch it also matches a group
that was found on a previous iteration of the outer loop.
This is a prime example where static checker warnings can prompt wrong
fixes. Frankly codacy should smart up to correctly analyze the
controlflow interdependency.
Sascha, please drop this patch.
Regards,
Lucas
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next prev parent reply other threads:[~2018-11-21 9:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 20:07 [PATCH v1 0/9] random fixes Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 1/9] net: e1000: fix "Uninitialized variable: phy_data" warning Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 2/9] pinctrl: tegra30: fix "Possible null pointer dereference: group" warning Oleksij Rempel
2018-11-21 9:16 ` Lucas Stach [this message]
2018-11-21 9:40 ` Oleksij Rempel
2018-11-21 10:01 ` Lucas Stach
2018-11-20 20:07 ` [PATCH v1 3/9] fs: closedir: remove uninitialized variable ret Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 4/9] fs: fix possible null pointer dereference of base Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 5/9] mfd: da9063: fix wrong NULL pointer test Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 6/9] usb: at91_udc: remove useless NULL check Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 7/9] mtd: atmel_nand: remove erroneous case Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 8/9] usb: musb: fix possible out of bounds access Oleksij Rempel
2018-11-20 20:07 ` [PATCH v1 9/9] lib: lodepng: remove useless test Oleksij Rempel
2018-11-21 8:08 ` [PATCH v1 0/9] random fixes Sascha Hauer
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