Commit f9092f35 authored by Jonathan Steel's avatar Jonathan Steel Committed by Linus Torvalds

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: default avatarJonathan Steel <jon.steel@esentire.com>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Acked-by: default avatarSimon Horman <horms@verge.net.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 39f00c08
......@@ -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;
......
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