From: Jonathan Steel <jon.steel@xxxxxxxxxxxx>
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 at esentire.com>
Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
---
kernel/kexec.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 59f3f0d..aef2653 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -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;
--
1.5.3.rc6.17.g1911
