On Sunday 01 December 2013 04:45:01 Greg KH wrote: > On Sat, Nov 30, 2013 at 11:58:23PM +0100, Pavel Machek wrote: > > On Sat 2013-11-30 14:05:53, Greg KH wrote: > > > On Sat, Nov 30, 2013 at 09:42:37PM +0100, Pavel Machek wrote: > > > > mmap in tidspbridge is missing range-checks. For now, > > > > make this interface root-only, so that it does not > > > > cause security problems. > > > > > > Please fix this properly and don't paper over the real > > > problem here. > > > > Well, if the driver is left uncompilable, I'm pretty sure it > > will bitrot. > > > > I do have the hardware, but I'm pretty sure current mailine > > does not have enough support to boot Maemo, so it is non > > trivial for me to test changes here. > > > > And yes, I'd like to get N900 to better shape, but there's > > more urgent work to do there. Such as "make sure N900 still > > boots once omap moves away from device files". > > > > [It seems like check should be that > > > > vma->vm_pgoff << PAGE_SHIFT >= pdata->phys_mempool_base and > > vma->vm_end - vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT - > > pdata->phys_mempool_base) <= pdata->phys_mempool_size . > > > > But... this is some kind of DSP coprocessor, and I am not > > sure if just exposing its address space to untrusted > > processes is good idea. > > > > Heck, are you sure this is security problem in the first > > place? Yes, it is unchecked mmap. So what? If the device is > > 600 root.root, and if the DSP can take over main system, > > > > if (!capable(CAP_SYS_RAWIO)) > > > > return -EPERM; > > Will that break userspace? Who opens and mmaps this device? > If you don't know if users do this, how can you say this > patch isn't going to break things just as much as not having > the driver there at all? > > thanks, > > greg k-h
Maemo and harmattan userspace using gst-dsp (gstreamer plugin) for using tidspbridge. It opening /dev/DspBridge and then it calling: mmap(NULL, seg->size, PROT_READ | PROT_WRITE, MAP_SHARED | 0x2000 /* MAP_LOCKED */, handle, seg->base_pa); Because it is gstreamer plugin, every application can use it (under non root too). Can you check if above problematic kernel code is what this gst-dsp mmap calling? -- Pali Rohár pali.ro...@gmail.com
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