Commit f9092f35 authored Sep 22, 2008 by Jonathan Steel Committed by Linus Torvalds Sep 23, 2008

kexec: fix segmentation fault in kimage_add_entry



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 <jon.steel@esentire.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 39f00c08

kernel/kexec.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -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;
		break;