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authorMike Kravetz <mike.kravetz@oracle.com>2020-08-12 04:31:35 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-12 20:57:56 +0300
commit15568299b7d9988063afce60731df605ab236e2a (patch)
tree228fe998eda7c9733a279192d14d013c461c95e8
parent619b5b469bcab84ea3bee1d8d04451c781d23feb (diff)
downloadlinux-15568299b7d9988063afce60731df605ab236e2a.tar.xz
hugetlbfs: prevent filesystem stacking of hugetlbfs
syzbot found issues with having hugetlbfs on a union/overlay as reported in [1]. Due to the limitations (no write) and special functionality of hugetlbfs, it does not work well in filesystem stacking. There are no know use cases for hugetlbfs stacking. Rather than making modifications to get hugetlbfs working in such environments, simply prevent stacking. [1] https://lore.kernel.org/linux-mm/000000000000b4684e05a2968ca6@google.com/ Reported-by: syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com Suggested-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Miklos Szeredi <mszeredi@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Colin Walters <walters@verbum.org> Link: http://lkml.kernel.org/r/80f869aa-810d-ef6c-8888-b46cee135907@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/hugetlbfs/inode.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 523954d00dff..b5c109703daa 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1364,6 +1364,12 @@ hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_magic = HUGETLBFS_MAGIC;
sb->s_op = &hugetlbfs_ops;
sb->s_time_gran = 1;
+
+ /*
+ * Due to the special and limited functionality of hugetlbfs, it does
+ * not work well as a stacking filesystem.
+ */
+ sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx));
if (!sb->s_root)
goto out_free;