This is a note to let you know that I've just added the patch titled
efi/libstub: Fix boundary checking in efi_high_alloc()
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
efi-libstub-fix-boundary-checking-in-efi_high_alloc.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7ed620bb343f434f8a85f830020c04988df2a140 Mon Sep 17 00:00:00 2001
From: Yinghai Lu <yinghai@xxxxxxxxxx>
Date: Thu, 19 Feb 2015 20:18:03 -0800
Subject: efi/libstub: Fix boundary checking in efi_high_alloc()
From: Yinghai Lu <yinghai@xxxxxxxxxx>
commit 7ed620bb343f434f8a85f830020c04988df2a140 upstream.
While adding support loading kernel and initrd above 4G to grub2 in legacy
mode, I was referring to efi_high_alloc().
That will allocate buffer for kernel and then initrd, and initrd will
use kernel buffer start as limit.
During testing found two buffers will be overlapped when initrd size is
very big like 400M.
It turns out efi_high_alloc() boundary checking is not right.
end - size will be the new start, and should not compare new
start with max, we need to make sure end is smaller than max.
[ Basically, with the current efi_high_alloc() code it's possible to
allocate memory above 'max', because efi_high_alloc() doesn't check
that the tail of the allocation is below 'max'.
If you have an EFI memory map with a single entry that looks like so,
[0xc0000000-0xc0004000]
And want to allocate 0x3000 bytes below 0xc0003000 the current code
will allocate [0xc0001000-0xc0004000], not [0xc0000000-0xc0003000]
like you would expect. - Matt ]
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/efi/libstub/efi-stub-helper.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -170,12 +170,12 @@ again:
start = desc->phys_addr;
end = start + desc->num_pages * (1UL << EFI_PAGE_SHIFT);
- if ((start + size) > end || (start + size) > max)
- continue;
-
- if (end - size > max)
+ if (end > max)
end = max;
+ if ((start + size) > end)
+ continue;
+
if (round_down(end - size, align) < start)
continue;
Patches currently in stable-queue which might be from yinghai@xxxxxxxxxx are
queue-3.19/efi-libstub-fix-boundary-checking-in-efi_high_alloc.patch
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