From: Mikhail Malygin <m.malygin@yadro.com>
Date: Thu, 16 Jul 2020 22:03:41 +0300
Subject: RDMA/rxe: Prevent access to wr->next ptr afrer wr is posted to send
 queue
Patch-mainline: v5.9-rc1
Git-commit: 5f0b2a6093a4d9aab093964c65083fe801ef1e58
References: jsc#SLE-15176

rxe_post_send_kernel() iterates over linked list of wr's, until the
wr->next ptr is NULL.  However if we've got an interrupt after last wr is
posted, control may be returned to the code after send completion callback
is executed and wr memory is freed.

As a result, wr->next pointer may contain incorrect value leading to
panic. Store the wr->next on the stack before posting it.

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20200716190340.23453-1-m.malygin@yadro.com
Signed-off-by: Mikhail Malygin <m.malygin@yadro.com>
Signed-off-by: Sergey Kojushev <s.kojushev@yadro.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/sw/rxe/rxe_verbs.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -682,6 +682,7 @@ static int rxe_post_send_kernel(struct r
 	unsigned int mask;
 	unsigned int length = 0;
 	int i;
+	struct ib_send_wr *next;
 
 	while (wr) {
 		mask = wr_opcode_mask(wr->opcode, qp);
@@ -698,6 +699,8 @@ static int rxe_post_send_kernel(struct r
 			break;
 		}
 
+		next = wr->next;
+
 		length = 0;
 		for (i = 0; i < wr->num_sge; i++)
 			length += wr->sg_list[i].length;
@@ -708,7 +711,7 @@ static int rxe_post_send_kernel(struct r
 			*bad_wr = wr;
 			break;
 		}
-		wr = wr->next;
+		wr = next;
 	}
 
 	rxe_run_task(&qp->req.task, 1);