mm: vmap fix overflow

The new vmap allocator can wrap the address and get confused in the case
of large allocations or VMALLOC_END near the end of address space.

Problem reported by Christoph Hellwig on a 32-bit XFS workload.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Reported-by: Christoph Hellwig <hch@lst.de>
Cc: <stable@kernel.org>		[2.6.28.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 903cad46e796..ed3705e4b83f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -323,6 +323,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
         unsigned long addr;
         int purged = 0;
 
+        BUG_ON(!size);
         BUG_ON(size & ~PAGE_MASK);
 
         va = kmalloc_node(sizeof(struct vmap_area),
@@ -334,6 +335,9 @@ retry:
         addr = ALIGN(vstart, align);
 
         spin_lock(&vmap_area_lock);
+        if (addr + size - 1 < addr)
+                goto overflow;
+
         /* XXX: could have a last_hole cache */
         n = vmap_area_root.rb_node;
         if (n) {
@@ -365,6 +369,8 @@ retry:
 
                 while (addr + size > first->va_start && addr + size <= vend) {
                         addr = ALIGN(first->va_end + PAGE_SIZE, align);
+                        if (addr + size - 1 < addr)
+                                goto overflow;
 
                         n = rb_next(&first->rb_node);
                         if (n)
@@ -375,6 +381,7 @@ retry:
         }
 found:
         if (addr + size > vend) {
+overflow:
                 spin_unlock(&vmap_area_lock);
                 if (!purged) {
                         purge_vmap_area_lazy();