[PATCH] i386: Fix race in iounmap

We need to hold the vmlist_lock while doing change_page_attr, otherwise we
could reset someone else's mapping.

Requires previous patch to add __remove_vm_area

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/i386/mm/ioremap.c b/arch/i386/mm/ioremap.c
index db06f7399913..ab542792b27b 100644
--- a/arch/i386/mm/ioremap.c
+++ b/arch/i386/mm/ioremap.c
@@ -238,19 +238,21 @@ void iounmap(volatile void __iomem *addr)
                         addr < phys_to_virt(ISA_END_ADDRESS))
                 return;
 
-        p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
+        write_lock(&vmlist_lock);
+        p = __remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
         if (!p) { 
-                printk("__iounmap: bad address %p\n", addr);
-                return;
+                printk("iounmap: bad address %p\n", addr);
+                goto out_unlock;
         }
 
         if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
-                /* p->size includes the guard page, but cpa doesn't like that */
                 change_page_attr(virt_to_page(__va(p->phys_addr)),
                                  p->size >> PAGE_SHIFT,
                                  PAGE_KERNEL);
                 global_flush_tlb();
         } 
+out_unlock:
+        write_unlock(&vmlist_lock);
         kfree(p); 
 }