SUNRPC: Fix a use after free bug with the NFSv4.1 backchannel

The ->release_request() callback was designed to allow the transport layer
to do housekeeping after the RPC call is done. It cannot be used to free
the request itself, and doing so leads to a use-after-free bug in
xprt_release().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/linux/sunrpc/bc_xprt.h b/include/linux/sunrpc/bc_xprt.h
index d7152b451e21..7c91260c44a9 100644
--- a/include/linux/sunrpc/bc_xprt.h
+++ b/include/linux/sunrpc/bc_xprt.h
@@ -36,7 +36,6 @@ struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt);
 void xprt_free_bc_request(struct rpc_rqst *req);
 int xprt_setup_backchannel(struct rpc_xprt *, unsigned int min_reqs);
 void xprt_destroy_backchannel(struct rpc_xprt *, int max_reqs);
-void bc_release_request(struct rpc_task *);
 int bc_send(struct rpc_rqst *req);
 
 /*
@@ -59,6 +58,10 @@ static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
 {
         return 0;
 }
+
+static inline void xprt_free_bc_request(struct rpc_rqst *req)
+{
+}
 #endif /* CONFIG_NFS_V4_1 */
 #endif /* _LINUX_SUNRPC_BC_XPRT_H */