kexec: fix segmentation fault in kimage_add_entry
authorJonathan Steel <>
Mon, 22 Sep 2008 20:57:45 +0000 (13:57 -0700)
committerLinus Torvalds <>
Tue, 23 Sep 2008 15:09:14 +0000 (08:09 -0700)
A segmentation fault can occur in kimage_add_entry in kexec.c when loading
a kernel image into memory.  The fault occurs because a page is requested
by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the function may
actually return a page with gfp_mask GFP_HIGHUSER.  The high mem page is
returned because it was swapped with the kernel page due to the kernel
page being a page that will shortly be copied to.

This patch ensures that kimage_alloc_page returns a page that was created
with the correct gfp flags.

I have verified the change and fixed the whitespace damage of the original
patch.  Jonathan did a great job of tracking this down after he hit the
problem.  -- Eric

Signed-off-by: Jonathan Steel <>
Signed-off-by: Eric W. Biederman <>
Acked-by: Simon Horman <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>

index 59f3f0d..aef2653 100644 (file)
@@ -753,8 +753,14 @@ static struct page *kimage_alloc_page(struct kimage *image,
                        *old = addr | (*old & ~PAGE_MASK);
                        /* The old page I have found cannot be a
-                        * destination page, so return it.
+                        * destination page, so return it if it's
+                        * gfp_flags honor the ones passed in.
+                       if (!(gfp_mask & __GFP_HIGHMEM) &&
+                           PageHighMem(old_page)) {
+                               kimage_free_pages(old_page);
+                               continue;
+                       }
                        addr = old_addr;
                        page = old_page;