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Message-ID: <31360.1163109619@lwn.net>
Date: Thu, 09 Nov 2006 15:00:19 -0700
From: Jonathan Corbet <corbet@....net>
To: linux-kernel@...r.kernel.org
cc: akpm@...l.org
Subject: [PATCH] Prevent an oops in vmalloc_user()
Prevent an oops in vmalloc_user()
If an attempt to allocate memory with vmalloc_user() fails, the result
will be an oops when it tries to tweak the flags in the (non-existent)
VMA. One could argue that __find_vm_area() should not return a random
pointer on failure, but vmalloc_user() requires a check regardless.
Signed-off-by: Jonathan Corbet <corbet@....net>
--- 2.6.19-rc5/mm/vmalloc.c.orig 2006-11-09 13:51:38.000000000 -0700
+++ 2.6.19-rc5/mm/vmalloc.c 2006-11-09 13:52:10.000000000 -0700
@@ -532,10 +532,12 @@ void *vmalloc_user(unsigned long size)
void *ret;
ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
- write_lock(&vmlist_lock);
- area = __find_vm_area(ret);
- area->flags |= VM_USERMAP;
- write_unlock(&vmlist_lock);
+ if (ret) {
+ write_lock(&vmlist_lock);
+ area = __find_vm_area(ret);
+ area->flags |= VM_USERMAP;
+ write_unlock(&vmlist_lock);
+ }
return ret;
}
-
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