From: Chuck Lever <chuck.lever@oracle.com>
Date: Wed, 19 Jun 2019 14:32:38 +0000 (-0400)
Subject: xprtrdma: Fix use-after-free in rpcrdma_post_recvs
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=2d0abe36cf13fb7b577949fd1539326adddcc9bc;p=openwrt%2Fstaging%2Fblogic.git

xprtrdma: Fix use-after-free in rpcrdma_post_recvs

Dereference wr->next /before/ the memory backing wr has been
released. This issue was found by code inspection. It is not
expected to be a significant problem because it is in an error
path that is almost never executed.

Fixes: 7c8d9e7c8863 ("xprtrdma: Move Receive posting to ... ")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 84bb37924540..e71315e9dca2 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1553,10 +1553,11 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
 	rc = ib_post_recv(r_xprt->rx_ia.ri_id->qp, wr,
 			  (const struct ib_recv_wr **)&bad_wr);
 	if (rc) {
-		for (wr = bad_wr; wr; wr = wr->next) {
+		for (wr = bad_wr; wr;) {
 			struct rpcrdma_rep *rep;
 
 			rep = container_of(wr, struct rpcrdma_rep, rr_recv_wr);
+			wr = wr->next;
 			rpcrdma_recv_buffer_put(rep);
 			--count;
 		}