Messages in this thread | | | From | Linus Walleij <> | Date | Fri, 2 Nov 2018 10:24:53 +0100 | Subject | Re: [PATCH v2] gpiolib: Fix possible use after free on label |
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On Thu, Nov 1, 2018 at 4:27 PM Linus Walleij <linus.walleij@linaro.org> wrote: > On Thu, Nov 1, 2018 at 2:13 PM Muchun Song <smuchun@gmail.com> wrote: > > > gpiod_request_commit() copies the pointer to the label passed as > > an argument only to be used later. But there's a chance the caller > > could immediately free the passed string(e.g., local variable). > > This could trigger a use after free when we use gpio label(e.g., > > gpiochip_unlock_as_irq(), gpiochip_is_requested()). > > > > To be on the safe side: duplicate the string with kstrdup_const() > > so that if an unaware user passes an address to a stack-allocated > > buffer, we won't get the arbitrary label. > > > > Also fix gpiod_set_consumer_name(). > > > > Signed-off-by: Muchun Song <smuchun@gmail.com> > > I am still a bit worried about the kstrdup_const() that this > introduces.
Forget it. I realized after actually reading the code for kstrdup_const() that it really does exactly what we want.
I should stop assuming things are syntactic sugar in the kernel, we have some really smart people working with it...
Patch applied.
Yours, Linus Walleij
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