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    SubjectRe: [BUG] video: fbdev: broadsheetfb: Possible null function pointers
    Date
    On Friday, July 27, 2018 09:49:41 AM Jia-Ju Bai wrote:
    >
    > On 2018/7/26 22:34, Bartlomiej Zolnierkiewicz wrote:
    > > On Thursday, July 26, 2018 10:17:44 PM bai wrote:
    > >> In Linux-4.16, drivers/video/fbdev/broadsheetfb.c,
    > >>
    > >> 158. static void broadsheet_mmio_send_cmdargs(...) {
    > >> ......
    > >> 163. par->board->mmio_write(...);
    > >> ......
    > >> 166. par->board->mmio_write(...);
    > >> 167. }
    > >>
    > >> For x86 kernel configuration, I find that there is no assignment of the
    > >> function pointer ".mmio_write" in the kernel code.
    > >> So calling the function pointer in lines 163 and 166 may cause a null
    > >> pointer dereference.
    > >>
    > >> In this file, there are many calls to this function pointer...
    > > This is a platform driver and it won't be used on x86 (actually it is
    > > used only by single ARM PXA board). The dependency for FB_BROADSHEET
    > > in Kconfig file could be improved to i.e.
    > >
    > > depends on FB && (ARCH_PXA || COMPILE_TEST)
    > >
    > > but there is no bug there.
    >
    > Thanks for the reply :)
    > So I want to submit a patch of updating Kconfig in
    > drivers/video/fbdev/Kconfig:
    >
    > config FB_BROADSHEET
    > tristate "E-Ink Broadsheet/Epson S1D13521 controller support"
    > - depends on FB
    > + depends on FB && (ARCH_PXA || COMPILE_TEST)
    > select FB_SYS_FILLRECT
    > select FB_SYS_COPYAREA
    > select FB_SYS_IMAGEBLIT
    > select FB_SYS_FOPS
    > select FB_DEFERRED_IO
    >
    >
    > Do you think it is okay?

    Please read Documentation/process/submitting-patches.rst.

    Best regards,
    --
    Bartlomiej Zolnierkiewicz
    Samsung R&D Institute Poland
    Samsung Electronics

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