Commit 8fc312b3 authored Nov 30, 2019 by Mike Kravetz Committed by Linus Torvalds Dec 01, 2019

mm/hugetlbfs: fix error handling when setting up mounts

It is assumed that the hugetlbfs_vfsmount[] array will contain either a
valid vfsmount pointer or NULL for each hstate after initialization.
Changes made while converting to use fs_context broke this assumption.

While fixing the hugetlbfs_vfsmount issue, it was discovered that
init_hugetlbfs_fs never did correctly clean up when encountering a vfs
mount error.

It was found during code inspection.  A small memory allocation failure
would be the most likely cause of taking a error path with the bug.
This is unlikely to happen as this is early init code.

Link: http://lkml.kernel.org/r/94b6244d-2c24-e269-b12c-e3ba694b242d@oracle.com


Reported-by: Chengguang Xu <cgxu519@mykernel.net>
Fixes: 32021982 ("hugetlbfs: Convert to fs_context")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 55254636

fs/hugetlbfs/inode.c

+22 −9

Original line number	Diff line number	Diff line
		@@ -1461,28 +1461,41 @@ static int __init init_hugetlbfs_fs(void)
		sizeof(struct hugetlbfs_inode_info),
		0, SLAB_ACCOUNT, init_once);
		if (hugetlbfs_inode_cachep == NULL)
		goto out2;
		goto out;

		error = register_filesystem(&hugetlbfs_fs_type);
		if (error)
		goto out;
		goto out_free;

		/* default hstate mount is required */
		mnt = mount_one_hugetlbfs(&hstates[default_hstate_idx]);
		if (IS_ERR(mnt)) {
		error = PTR_ERR(mnt);
		goto out_unreg;
		}
		hugetlbfs_vfsmount[default_hstate_idx] = mnt;

		/* other hstates are optional */
		i = 0;
		for_each_hstate(h) {
		if (i == default_hstate_idx)
		continue;

		mnt = mount_one_hugetlbfs(h);
		if (IS_ERR(mnt) && i == 0) {
		error = PTR_ERR(mnt);
		goto out;
		}
		if (IS_ERR(mnt))
		hugetlbfs_vfsmount[i] = NULL;
		else
		hugetlbfs_vfsmount[i] = mnt;
		i++;
		}

		return 0;

		out:
		out_unreg:
		(void)unregister_filesystem(&hugetlbfs_fs_type);
		out_free:
		kmem_cache_destroy(hugetlbfs_inode_cachep);
		out2:
		out:
		return error;
		}
		fs_initcall(init_hugetlbfs_fs)

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