vm audit: add VM_DONTEXPAND to mmap for drivers that need it

Drivers that register a ->fault handler, but do not range-check the
offset argument, must set VM_DONTEXPAND in the vm_flags in order to
prevent an expanding mremap from overflowing the resource.

I've audited the tree and attempted to fix these problems (usually by
adding VM_DONTEXPAND where it is not obvious).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 8 insertions, 10 deletions

diff --git a/sound/oss/via82cxxx_audio.c b/sound/oss/via82cxxx_audio.c
index 5d3c0372df32..f95aa0946758 100644
--- a/sound/oss/via82cxxx_audio.c
+++ b/sound/oss/via82cxxx_audio.c
@@ -2104,6 +2104,7 @@ static struct page * via_mm_nopage (struct vm_area_struct * vma,
 {
         struct via_info *card = vma->vm_private_data;
         struct via_channel *chan = &card->ch_out;
+        unsigned long max_bufs;
         struct page *dmapage;
         unsigned long pgoff;
         int rd, wr;
@@ -2127,14 +2128,11 @@ static struct page * via_mm_nopage (struct vm_area_struct * vma,
         rd = card->ch_in.is_mapped;
         wr = card->ch_out.is_mapped;
 
-#ifndef VIA_NDEBUG
-        {
-        unsigned long max_bufs = chan->frag_number;
-        if (rd && wr) max_bufs *= 2;
-        /* via_dsp_mmap() should ensure this */
-        assert (pgoff < max_bufs);
-        }
-#endif
+        max_bufs = chan->frag_number;
+        if (rd && wr)
+                max_bufs *= 2;
+        if (pgoff >= max_bufs)
+                return NOPAGE_SIGBUS;
 
         /* if full-duplex (read+write) and we have two sets of bufs,
          * then the playback buffers come first, sez soundcard.c */
diff --git a/sound/usb/usx2y/usX2Yhwdep.c b/sound/usb/usx2y/usX2Yhwdep.c
index 6495534e5bf6..1558a5c4094f 100644
--- a/sound/usb/usx2y/usX2Yhwdep.c
+++ b/sound/usb/usx2y/usX2Yhwdep.c
@@ -84,7 +84,7 @@ static int snd_us428ctls_mmap(struct snd_hwdep * hw, struct file *filp, struct v
                 us428->us428ctls_sharedmem->CtlSnapShotLast = -2;
         }
         area->vm_ops = &us428ctls_vm_ops;
-        area->vm_flags |= VM_RESERVED;
+        area->vm_flags |= VM_RESERVED | VM_DONTEXPAND;
         area->vm_private_data = hw->private_data;
         return 0;
 }
diff --git a/sound/usb/usx2y/usx2yhwdeppcm.c b/sound/usb/usx2y/usx2yhwdeppcm.c
index 800b5cecfc80..117946f2debb 100644
--- a/sound/usb/usx2y/usx2yhwdeppcm.c
+++ b/sound/usb/usx2y/usx2yhwdeppcm.c
@@ -722,7 +722,7 @@ static int snd_usX2Y_hwdep_pcm_mmap(struct snd_hwdep * hw, struct file *filp, st
                 return -ENODEV;
         }
         area->vm_ops = &snd_usX2Y_hwdep_pcm_vm_ops;
-        area->vm_flags |= VM_RESERVED;
+        area->vm_flags |= VM_RESERVED | VM_DONTEXPAND;
         area->vm_private_data = hw->private_data;
         return 0;
 }