On Tuesday 20 June 2017 06:36 PM, Lad, Prabhakar wrote: > Hi Arnd, > > Thanks for the patch. > > On Fri, Jun 9, 2017 at 10:36 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: >> Now that the davinci drivers can be enabled in compile tests on other >> architectures, I ran into this warning on a 64-bit build: >> >> drivers/media/platform/davinci/dm644x_ccdc.c: In function 'ccdc_update_raw_params': >> drivers/media/platform/davinci/dm644x_ccdc.c:279:7: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast] >> >> While that looks fairly harmless (it would be fine on 32-bit), it was >> just the tip of the iceberg: >> >> - The function constantly mixes up pointers and phys_addr_t numbers >> - This is part of a 'VPFE_CMD_S_CCDC_RAW_PARAMS' ioctl command that is >> described as an 'experimental ioctl that will change in future kernels', >> but if we have users that probably won't happen. >> - The code to allocate the table never gets called after we copy_from_user >> the user input over the kernel settings, and then compare them >> for inequality. >> - We then go on to use an address provided by user space as both the >> __user pointer for input and pass it through phys_to_virt to come up >> with a kernel pointer to copy the data to. This looks like a trivially >> exploitable root hole. >> >> This patch disables all the obviously broken code, by zeroing out the >> sensitive data provided by user space. I also fix the type confusion >> here. If we think the ioctl has no stable users, we could consider >> just removing it instead. >> > I suspect there shouldn’t be possible users of this IOCTL, better of removing > the IOCTL itself. > > Sekhar your call, as the latest PSP releases for 644x use the media > controller framework. I do not have any personal experience with anyone using this support with latest kernels. I too am okay with removing the broken support. Since the header file that defines the ioctl is not in include/uapi/*, I guess it cannot be considered stable userspace ABI? Also, there are enough warnings about instability thrown in the comments surrounding the ioctl in include/media/davinci/vpfe_capture.h. Thanks, Sekhar
