From d781e3df710745fbbaee4eb07fd5b64331a1b175 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Fri, 6 Dec 2019 16:07:32 -0500 Subject: nfsd4: avoid NULL deference on strange COPY compounds With cross-server COPY we've introduced the possibility that the current or saved filehandle might not have fh_dentry/fh_export filled in, but we missed a place that assumed it was. I think this could be triggered by a compound like: PUTFH(foreign filehandle) GETATTR SAVEFH COPY First, check_if_stalefh_allowed sets no_verify on the first (PUTFH) op. Then op_func = nfsd4_putfh runs and leaves current_fh->fh_export NULL. need_wrongsec_check returns true, since this PUTFH has OP_IS_PUTFH_LIKE set and GETATTR does not have OP_HANDLES_WRONGSEC set. We should probably also consider tightening the checks in check_if_stalefh_allowed and double-checking that we don't assume the filehandle is verified elsewhere in the compound. But I think this fixes the immediate issue. Reported-by: Dan Carpenter Fixes: 4e48f1cccab3 "NFSD: allow inter server COPY to have... " Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4proc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index d33c39c18cdd..30c75b961d68 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -2368,7 +2368,8 @@ nfsd4_proc_compound(struct svc_rqst *rqstp) if (op->opdesc->op_flags & OP_CLEAR_STATEID) clear_current_stateid(cstate); - if (need_wrongsec_check(rqstp)) + if (current_fh->fh_export && + need_wrongsec_check(rqstp)) op->status = check_nfsd_access(current_fh->fh_export, rqstp); } encode_op: -- cgit v1.2.3