Re: [BUG] video: fbdev: broadsheetfb: Possible null function pointers

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(...) { ......

159. par->board->mmio_write(...);
         ......
     

160. par->board->mmio_write(...);
     

161. }

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.

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