[PATCH 4.14 172/218] xprtrdma: treat all calls not a bcall when bc_serv is NULL

Greg Kroah-Hartman
2022-06-13T11:06:16Z

From: Kinglong Mee <kinglongmee@gmail.com>

[ Upstream commit 11270e7ca268e8d61b5d9e5c3a54bd1550642c9c ]

When a rdma server returns a fault format reply, nfs v3 client may
treats it as a bcall when bc service is not exist.

The debug message at rpcrdma_bc_receive_call are,

[56579.837169] RPC: rpcrdma_bc_receive_call: callback XID
00000001, length=20
[56579.837174] RPC: rpcrdma_bc_receive_call: 00 00 00 01 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 04

After that, rpcrdma_bc_receive_call will meets NULL pointer as,

[ 226.057890] BUG: unable to handle kernel NULL pointer dereference at
00000000000000c8
...
[ 226.058704] RIP: 0010:_raw_spin_lock+0xc/0x20
...
[ 226.059732] Call Trace:
[ 226.059878] rpcrdma_bc_receive_call+0x138/0x327 [rpcrdma]
[ 226.060011] __ib_process_cq+0x89/0x170 [ib_core]
[ 226.060092] ib_cq_poll_work+0x26/0x80 [ib_core]
[ 226.060257] process_one_work+0x1a7/0x360
[ 226.060367] ? create_worker+0x1a0/0x1a0
[ 226.060440] worker_thread+0x30/0x390
[ 226.060500] ? create_worker+0x1a0/0x1a0
[ 226.060574] kthread+0x116/0x130
[ 226.060661] ? kthread_flush_work_fn+0x10/0x10
[ 226.060724] ret_from_fork+0x35/0x40
...

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/xprtrdma/rpc_rdma.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 991d5a96f35b..030bf17a20b6 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -974,6 +974,7 @@ rpcrdma_is_bcall(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep,
__be32 xid, __be32 proc)
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
{
+ struct rpc_xprt *xprt = &r_xprt->rx_xprt;
struct xdr_stream *xdr = &rep->rr_stream;
__be32 *p;

@@ -997,6 +998,10 @@ rpcrdma_is_bcall(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep,
if (*p != cpu_to_be32(RPC_CALL))
return false;

+ /* No bc service. */
+ if (xprt->bc_serv == NULL)
+ return false;
+
/* Now that we are sure this is a backchannel call,
* advance to the RPC header.
*/
--
2.35.1