[PATCH] nfsd: call op_release, even when op_func returns an error

[Jeff Layton <jlayton@kernel.org>]

For ops with "trivial" replies, nfsd4_encode_operation will shortcut
most of the encoding work and skip to just marshalling up the status.
One of the things it skips is calling op_release. This could cause a
memory leak in the layoutget codepath if there is an error at an
inopportune time.

Have the compound processing engine always call op_release, even when
op_func sets an error in op->status. With this change, we also need
nfsd4_block_get_device_info_scsi to set the gd_device pointer to NULL
on error to avoid a double free.

Reported-by: Zhi Li <yieli@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2181403
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/blocklayout.c |  1 +
 fs/nfsd/nfs4xdr.c     | 13 +++++++------
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index 04697f8dc37d..01d7fd108cf3 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -297,6 +297,7 @@ nfsd4_block_get_device_info_scsi(struct super_block *sb,
 
 out_free_dev:
 	kfree(dev);
+	gdp->gd_device = NULL;
 	return ret;
 }
 
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index e12e5a4ad502..6b675fbdabd0 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -5402,7 +5402,7 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
 	p = xdr_reserve_space(xdr, 8);
 	if (!p) {
 		WARN_ON_ONCE(1);
-		return;
+		goto release;
 	}
 	*p++ = cpu_to_be32(op->opnum);
 	post_err_offset = xdr->buf->len;
@@ -5418,8 +5418,6 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
 	op->status = encoder(resp, op->status, &op->u);
 	if (op->status)
 		trace_nfsd_compound_encode_err(rqstp, op->opnum, op->status);
-	if (opdesc && opdesc->op_release)
-		opdesc->op_release(&op->u);
 	xdr_commit_encode(xdr);
 
 	/* nfsd4_check_resp_size guarantees enough room for error status */
@@ -5460,11 +5458,14 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
 	}
 status:
 	*p = op->status;
+release:
+	if (opdesc && opdesc->op_release)
+		opdesc->op_release(&op->u);
 }
 
-/* 
- * Encode the reply stored in the stateowner reply cache 
- * 
+/*
+ * Encode the reply stored in the stateowner reply cache
+ *
  * XDR note: do not encode rp->rp_buflen: the buffer contains the
  * previously sent already encoded operation.
  */
-- 
2.39.2