From 65170b60571ec10a7c4d9d4171df86fa9dee677a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 11 May 2018 17:03:19 -0400 Subject: [PATCH] nfsd: vfs_mkdir() might succeed leaving dentry negative unhashed That can (and does, on some filesystems) happen - ->mkdir() (and thus vfs_mkdir()) can legitimately leave its argument negative and just unhash it, counting upon the lookup to pick the object we'd created next time we try to look at that name. Some vfs_mkdir() callers forget about that possibility... Acked-by: J. Bruce Fields Signed-off-by: Al Viro --- fs/nfsd/vfs.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 2410b093a2e61..b0555d7d8200f 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1201,6 +1201,28 @@ nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp, break; case S_IFDIR: host_err = vfs_mkdir(dirp, dchild, iap->ia_mode); + if (!host_err && unlikely(d_unhashed(dchild))) { + struct dentry *d; + d = lookup_one_len(dchild->d_name.name, + dchild->d_parent, + dchild->d_name.len); + if (IS_ERR(d)) { + host_err = PTR_ERR(d); + break; + } + if (unlikely(d_is_negative(d))) { + dput(d); + err = nfserr_serverfault; + goto out; + } + dput(resfhp->fh_dentry); + resfhp->fh_dentry = dget(d); + err = fh_update(resfhp); + dput(dchild); + dchild = d; + if (err) + goto out; + } break; case S_IFCHR: case S_IFBLK: -- 2.39.5