Messages in this thread |  | | Date | Sat, 28 Dec 2019 13:48:24 +0000 | From | Russell King - ARM Linux admin <> | Subject | Re: [PATCH] board-dm644x-evm: fix 2 missing-check bugs in evm_led_setup() |
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On Sat, Dec 28, 2019 at 09:19:30PM +0800, Gen Zhang wrote: > On Fri, Dec 27, 2019 at 04:01:42PM +0000, Russell King - ARM Linux admin wrote: > > On Fri, Dec 27, 2019 at 10:39:21AM +0800, Gen Zhang wrote: > > > In evm_led_setup(), the allocation result of platform_device_alloc() and > > > platform_device_add_data() should be checked. > > > > > > Signed-off-by: Gen Zhang <blackgod016574@gmail.com> > > > --- > > > diff --git a/arch/arm/mach-davinci/board-dm644x-evm.c b/arch/arm/mach-davinci/board-dm644x-evm.c > > > index 9d87d4e..9cd2785 100644 > > > --- a/arch/arm/mach-davinci/board-dm644x-evm.c > > > +++ b/arch/arm/mach-davinci/board-dm644x-evm.c > > > @@ -352,15 +352,20 @@ evm_led_setup(struct i2c_client *client, int gpio, unsigned ngpio, void *c) > > > * device unregistration ... > > > */ > > > evm_led_dev = platform_device_alloc("leds-gpio", 0); > > > - platform_device_add_data(evm_led_dev, > > > + if (!evm_led_dev) > > > + return -ENOMEM; > > > + status = platform_device_add_data(evm_led_dev, > > > &evm_led_data, sizeof evm_led_data); > > > + if (status) > > > + goto err; > > > > > > evm_led_dev->dev.parent = &client->dev; > > > status = platform_device_add(evm_led_dev); > > > - if (status < 0) { > > > - platform_device_put(evm_led_dev); > > > - evm_led_dev = NULL; > > > - } > > > + if (status) > > > + goto err; > > > +err: > > > + platform_device_put(evm_led_dev); > > > + evm_led_dev = NULL; > > > > Please look again at the above change very closely. You will want to > > send an updated patch. > > > > -- > > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ > > FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up > > According to speedtest.net: 11.9Mbps down 500kbps up > > Thanks for your reply. You mean the if (state < 0 ) to if (state) or > anything else? Please point out directly.
This is the old everything-successful path through the code:
platform_device_alloc() platform_device_add_data() platform_device_add() evm_led_dev is set to the device
This is the new everything-successful path through the code:
platform_device_alloc() platform_device_add_data() platform_device_add() platform_device_put() evm_led_dev = NULL
And, specifically, the code sequence (I quote from your patch):
if (status) goto err; err:
is very stupid; it might as well not exist at all.
Since other code references evm_led_dev, one can assume that we do not want it to be NULL for the success path. So, taking all this together, your patch is very very wrong, and I also find it very worrying too.
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
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