This is a note to let you know that I've just added the patch titled
s390/pci_mmio: fully validate the VMA before calling follow_pte()
to the 5.10-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:
s390-pci_mmio-fully-validate-the-vma-before-calling-follow_pte.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a8b92b8c1eac8d655a97b1e90f4d83c25d9b9a18 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <david@xxxxxxxxxx>
Date: Thu, 9 Sep 2021 16:59:42 +0200
Subject: s390/pci_mmio: fully validate the VMA before calling follow_pte()
From: David Hildenbrand <david@xxxxxxxxxx>
commit a8b92b8c1eac8d655a97b1e90f4d83c25d9b9a18 upstream.
We should not walk/touch page tables outside of VMA boundaries when
holding only the mmap sem in read mode. Evil user space can modify the
VMA layout just before this function runs and e.g., trigger races with
page table removal code since commit dd2283f2605e ("mm: mmap: zap pages
with read mmap_sem in munmap").
find_vma() does not check if the address is >= the VMA start address;
use vma_lookup() instead.
Reviewed-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap")
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/pci/pci_mmio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/pci/pci_mmio.c
+++ b/arch/s390/pci/pci_mmio.c
@@ -128,7 +128,7 @@ static long get_pfn(unsigned long user_a
mmap_read_lock(current->mm);
ret = -EINVAL;
vma = find_vma(current->mm, user_addr);
- if (!vma)
+ if (!vma || user_addr < vma->vm_start)
goto out;
ret = -EACCES;
if (!(vma->vm_flags & access))
Patches currently in stable-queue which might be from david@xxxxxxxxxx are
queue-5.10/s390-pci_mmio-fully-validate-the-vma-before-calling-follow_pte.patch
