Re: [PATCH] gpio: davinci: Fix potential buffer overflow

[Aleksandr Mishin]

28.03.2024 18:27, Alexander Lobakin пишет:
> From: Aleksandr Mishin <amishin@xxxxxxxxxx>
> Date: Thu, 28 Mar 2024 12:10:21 +0300
>
> > In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and
> > array 'offset_array' of size 5 can lead to a buffer overflow, since the index
> > 'bank' can have an out of range value 63.
> > Fix this bug by limiting top index value.
> >
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> >
> > Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller")
> > Signed-off-by: Aleksandr Mishin <amishin@xxxxxxxxxx>
> > ---
> >   drivers/gpio/gpio-davinci.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c
> > index bb499e362912..b65df1f2b83f 100644
> > --- a/drivers/gpio/gpio-davinci.c
> > +++ b/drivers/gpio/gpio-davinci.c
> > @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev)
> >   	spin_lock_init(&chips->lock);
> >   
> >   	nbank = DIV_ROUND_UP(ngpio, 32);
> > +    if (nbank > MAX_REGS_BANKS || nbank > 5) {
> > +        nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5;
> > +	}
>
> Static analysis warnings make no sense until you provide a reliable way
> to trigger the problem on real systems.
>
> >   	for (bank = 0; bank < nbank; bank++)
> >   		chips->regs[bank] = gpio_base + offset_array[bank];
> >   
>
> Thanks,
> Olek

I can only see the code at this time. And I see the following:
1. In some configurations CONFIG_ARCH_NR_GPIO value is 2048. So nbank 
value can be 64.
2. Previously, a patch was proposed that removes restrictions on the 
number of GPIOs 
(https://lore.kernel.org/all/cb540a9d73cad36d288664f8b275c6308a4a3168.1662116601.git.christophe.leroy@xxxxxxxxxx/).

--
Kind regards
Aleksandr