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>

8 files changed, 13 insertions, 16 deletions

diff --git a/drivers/char/drm/drm_vm.c b/drivers/char/drm/drm_vm.c
index e8d50af58201..ef5e6b130c48 100644
--- a/drivers/char/drm/drm_vm.c
+++ b/drivers/char/drm/drm_vm.c
@@ -506,6 +506,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
         vma->vm_ops = &drm_vm_dma_ops;
 
         vma->vm_flags |= VM_RESERVED;   /* Don't swap */
+        vma->vm_flags |= VM_DONTEXPAND;
 
         vma->vm_file = filp;    /* Needed for drm_vm_open() */
         drm_vm_open_locked(vma);
@@ -655,6 +656,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
                 return -EINVAL; /* This should never happen. */
         }
         vma->vm_flags |= VM_RESERVED;   /* Don't swap */
+        vma->vm_flags |= VM_DONTEXPAND;
 
         vma->vm_file = filp;    /* Needed for drm_vm_open() */
         drm_vm_open_locked(vma);
diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
index 82f2e27dca7d..ff146c2b08fd 100644
--- a/drivers/char/mspec.c
+++ b/drivers/char/mspec.c
@@ -283,7 +283,7 @@ mspec_mmap(struct file *file, struct vm_area_struct *vma,
         vdata->refcnt = ATOMIC_INIT(1);
         vma->vm_private_data = vdata;
 
-        vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP);
+        vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
         vma->vm_ops = &mspec_vm_ops;
diff --git a/fs/ncpfs/mmap.c b/fs/ncpfs/mmap.c
index a94473d3072c..5d8dcb9ee326 100644
--- a/fs/ncpfs/mmap.c
+++ b/fs/ncpfs/mmap.c
@@ -50,10 +50,6 @@ static int ncp_file_mmap_fault(struct vm_area_struct *area,
         pos = vmf->pgoff << PAGE_SHIFT;
 
         count = PAGE_SIZE;
-        if ((unsigned long)vmf->virtual_address + PAGE_SIZE > area->vm_end) {
-                WARN_ON(1); /* shouldn't happen? */
-                count = area->vm_end - (unsigned long)vmf->virtual_address;
-        }
         /* what we can read in one go */
         bufsize = NCP_SERVER(inode)->buffer_size;
 
diff --git a/kernel/relay.c b/kernel/relay.c
index 61134eb7a0c8..7c0373322f18 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -92,6 +92,7 @@ static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
                 return -EINVAL;
 
         vma->vm_ops = &relay_file_mmap_ops;
+        vma->vm_flags |= VM_DONTEXPAND;
         vma->vm_private_data = buf;
         buf->chan->cb->buf_mapped(buf, filp);
 
diff --git a/mm/mmap.c b/mm/mmap.c
index d2b6d44962b7..8295577a83b2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2216,7 +2216,7 @@ int install_special_mapping(struct mm_struct *mm,
         vma->vm_start = addr;
         vma->vm_end = addr + len;
 
-        vma->vm_flags = vm_flags | mm->def_flags;
+        vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
         vma->vm_ops = &special_mapping_vmops;
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;
 }