[PATCH 5.4 127/191] mm/hugetlbfs: fix error handling when setting up mounts

Greg Kroah-Hartman
2020-01-02T22:16:02Z

From: Mike Kravetz <mike.kravetz@oracle.com>

[ Upstream commit 8fc312b32b25c6b0a8b46fab4df8c68df5af1223 ]

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: 32021982a324 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/hugetlbfs/inode.c | 31 ++++++++++++++++++++++---------
1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index a478df035651..26e3906c18fe 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -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;
- }
- hugetlbfs_vfsmount[i] = mnt;
+ 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)
--
2.20.1