From: David Hildenbrand Date: Thu, 9 Sep 2021 16:22:44 +0000 (+0200) Subject: s390/uv: fully validate the VMA before calling follow_page() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=46c22ffd2772201662350bc7b94b9ea9d3ee5ac2;p=linux.git s390/uv: fully validate the VMA before calling follow_page() 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 Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Reviewed-by: Liam R. Howlett Link: https://lore.kernel.org/r/20210909162248.14969-6-david@redhat.com Signed-off-by: Christian Borntraeger --- diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index 5a656c7b7a67a..f95ccbd396925 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -212,7 +212,7 @@ again: 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; /*