mm: don't allow ioremapping of ranges larger than vmalloc space

When running with a 16M IOREMAP_MAX_ORDER (on armv7) we found that the
vmlist search routine in __get_vm_area_node can mistakenly allow a driver
to ioremap a range larger than vmalloc space.

If at the time of the ioremap all existing vmlist areas sit below the
determined alignment then the search routine continues past all entries and
exits the for loop - straight into the found: label - without ever testing
for integer wrapping or that the requested size fits.

We were seeing a driver successfully ioremap 128M of flash even though
there was only 120M of vmalloc space.  From that point the system was left
with the remainder of the first 16M of space to vmalloc/ioremap within.

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4efc41a6e2abefae709cfe0f8d59bcd0844c8dfa..0536dde139d1e1f6f28fc93ccd05a9fc337e2c7e 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -254,6 +254,10 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long fl
                if (addr > end - size)
                        goto out;
        }
+       if ((size + addr) < addr)
+               goto out;
+       if (addr > end - size)
+               goto out;
 
 found:
        area->next = *p;