From 9b1dcbc8cf4679ecf090b343ac31bda6e55ddabe Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 12 Feb 2015 10:14:51 -0500 Subject: [PATCH] xprtrdma: Store RDMA credits in unsigned variables Dan Carpenter's static checker pointed out: net/sunrpc/xprtrdma/rpc_rdma.c:879 rpcrdma_reply_handler() warn: can 'credits' be negative? "credits" is defined as an int. The credits value comes from the server as a 32-bit unsigned integer. A malicious or broken server can plant a large unsigned integer in that field which would result in an underflow in the following logic, potentially triggering a deadlock of the mount point by blocking the client from issuing more RPC requests. net/sunrpc/xprtrdma/rpc_rdma.c: 876 credits = be32_to_cpu(headerp->rm_credit); 877 if (credits == 0) 878 credits = 1; /* don't deadlock */ 879 else if (credits > r_xprt->rx_buf.rb_max_requests) 880 credits = r_xprt->rx_buf.rb_max_requests; 881 882 cwnd = xprt->cwnd; 883 xprt->cwnd = credits << RPC_CWNDSHIFT; 884 if (xprt->cwnd > cwnd) 885 xprt_release_rqst_cong(rqst->rq_task); Reported-by: Dan Carpenter Fixes: eba8ff660b2d ("xprtrdma: Move credit update to RPC . . .") Signed-off-by: Chuck Lever Signed-off-by: Anna Schumaker --- net/sunrpc/xprtrdma/rpc_rdma.c | 3 ++- net/sunrpc/xprtrdma/xprt_rdma.h | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 7e9acd9361c5..91ffde82fa0c 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -738,8 +738,9 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep) struct rpc_xprt *xprt = rep->rr_xprt; struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); __be32 *iptr; - int credits, rdmalen, status; + int rdmalen, status; unsigned long cwnd; + u32 credits; /* Check status. If bad, signal disconnect and return rep to pool */ if (rep->rr_len == ~0U) { diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index d1b70397c60f..0a16fb6f0885 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -285,7 +285,7 @@ rpcr_to_rdmar(struct rpc_rqst *rqst) */ struct rpcrdma_buffer { spinlock_t rb_lock; /* protects indexes */ - int rb_max_requests;/* client max requests */ + u32 rb_max_requests;/* client max requests */ struct list_head rb_mws; /* optional memory windows/fmrs/frmrs */ struct list_head rb_all; int rb_send_index;