lkml.org 
[lkml]   [2021]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH RFC 5/9] s390/uv: fully validate the VMA before calling follow_page()
Date
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.

Fixes: 214d9bbcd3a6 ("s390/mm: provide memory management functions for protected KVM guests")
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/s390/kernel/uv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index aeb0a15bcbb7..193205fb2777 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -227,7 +227,7 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
uaddr = __gmap_translate(gmap, gaddr);
if (IS_ERR_VALUE(uaddr))
goto out;
- vma = find_vma(gmap->mm, uaddr);
+ vma = vma_lookup(gmap->mm, uaddr);
if (!vma)
goto out;
/*
--
2.31.1
\
 
 \ /
  Last update: 2021-09-09 17:01    [W:0.076 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site