| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.5 013/399] nfsd4: avoid NULL deference on strange COPY compounds | Date | Fri, 21 Feb 2020 08:35:38 +0100 |
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From: J. Bruce Fields <bfields@redhat.com>
[ Upstream commit d781e3df710745fbbaee4eb07fd5b64331a1b175 ]
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 <dan.carpenter@oracle.com> Fixes: 4e48f1cccab3 "NFSD: allow inter server COPY to have... " Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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 4798667af647c..4d1d0bf8e385f 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -2025,7 +2025,8 @@ 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: -- 2.20.1
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