From: Chuck Lever chuck.lever@oracle.com
stable inclusion from linux-4.19.155 commit 88401813fcec150ff179e731364fc19af1e6632f
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commit 6b3dccd48de8a4c650b01499a0b09d1e2279649e upstream.
There's no protection in nfsd_dispatch() against a NULL .pc_func helpers. A malicious NFS client can trigger a crash by invoking the unused/unsupported NFSv2 ROOT or WRITECACHE procedures.
The current NFSD dispatcher does not support returning a void reply to a non-NULL procedure, so the reply to both of these is wrong, for the moment.
Cc: stable@vger.kernel.org Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- fs/nfsd/nfsproc.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c index 0d20fd161225..01f7ce1ae127 100644 --- a/fs/nfsd/nfsproc.c +++ b/fs/nfsd/nfsproc.c @@ -118,6 +118,13 @@ nfsd_proc_setattr(struct svc_rqst *rqstp) return nfsd_return_attrs(nfserr, resp); }
+/* Obsolete, replaced by MNTPROC_MNT. */ +static __be32 +nfsd_proc_root(struct svc_rqst *rqstp) +{ + return nfs_ok; +} + /* * Look up a path name component * Note: the dentry in the resp->fh may be negative if the file @@ -201,6 +208,13 @@ nfsd_proc_read(struct svc_rqst *rqstp) return fh_getattr(&resp->fh, &resp->stat); }
+/* Reserved */ +static __be32 +nfsd_proc_writecache(struct svc_rqst *rqstp) +{ + return nfs_ok; +} + /* * Write data to a file * N.B. After this call resp->fh needs an fh_put @@ -615,6 +629,7 @@ static const struct svc_procedure nfsd_procedures2[18] = { .pc_xdrressize = ST+AT, }, [NFSPROC_ROOT] = { + .pc_func = nfsd_proc_root, .pc_decode = nfssvc_decode_void, .pc_encode = nfssvc_encode_void, .pc_argsize = sizeof(struct nfsd_void), @@ -652,6 +667,7 @@ static const struct svc_procedure nfsd_procedures2[18] = { .pc_xdrressize = ST+AT+1+NFSSVC_MAXBLKSIZE_V2/4, }, [NFSPROC_WRITECACHE] = { + .pc_func = nfsd_proc_writecache, .pc_decode = nfssvc_decode_void, .pc_encode = nfssvc_encode_void, .pc_argsize = sizeof(struct nfsd_void),