userns: Don't let unprivileged users trick privileged users into setting the id_map

[~andy/linux] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 6466699b16cbca1a26c8792f9d484925a23df005..0db0de1c2fbee21e0e9919af66021b190d789731 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1940,7 +1940,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 
        /* Check the cache first. */
        /* (Cache hit rate is typically around 35%.) */
-       vma = mm->mmap_cache;
+       vma = ACCESS_ONCE(mm->mmap_cache);
        if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
                struct rb_node *rb_node;