RE: [PATCH] staging: lustre: ko2iblnd: check copy_from_iter/copy_to_iter return code

[Shehata, Amir]

The changes look good to me.

-----Original Message-----
From: James Simmons [mailto:jsimmons@xxxxxxxxxxxxx] 
Sent: Saturday, July 15, 2017 8:32 AM
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; devel@xxxxxxxxxxxxxxxxxxxx; Dilger, Andreas <andreas.dilger@xxxxxxxxx>; Drokin, Oleg <oleg.drokin@xxxxxxxxx>; Arnd Bergmann <arnd@xxxxxxxx>; Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Shehata, Amir <amir.shehata@xxxxxxxxx>; Olaf Weber <olaf.weber@xxxxxxx>; Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; Lustre Development List <lustre-devel@xxxxxxxxxxxxxxxx>; stable@xxxxxxxxxxxxxxx; James Simmons <jsimmons@xxxxxxxxxxxxx>
Subject: [PATCH] staging: lustre: ko2iblnd: check copy_from_iter/copy_to_iter return code

From: Arnd Bergmann <arnd@xxxxxxxx>

We now get a helpful warning for code that calls copy_{from,to}_iter without checking the return value, introduced by commit aa28de275a24
("iov_iter/hardening: move object size checks to inlined part").

drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c: In function 'kiblnd_send':
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c:1643:2: error: ignoring return value of 'copy_from_iter', declared with attribute warn_unused_result [-Werror=unused-result]
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c: In function 'kiblnd_recv':
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c:1744:3: error: ignoring return value of 'copy_to_iter', declared with attribute warn_unused_result [-Werror=unused-result]

In case we get short copies here, we may get incorrect behavior.
I've added failure handling for both rx and tx now, returning -EFAULT as expected.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
Signed-off-by: Amir Shehata <amir.shehata@xxxxxxxxx>
---
 .../staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c    | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
index 85b242e..8fc191d 100644
--- a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
+++ b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
@@ -1640,8 +1640,13 @@ static int kiblnd_resolve_addr(struct rdma_cm_id *cmid,
 	ibmsg = tx->tx_msg;
 	ibmsg->ibm_u.immediate.ibim_hdr = *hdr;
 
-	copy_from_iter(&ibmsg->ibm_u.immediate.ibim_payload, IBLND_MSG_SIZE,
-		       &from);
+	rc = copy_from_iter(&ibmsg->ibm_u.immediate.ibim_payload, payload_nob,
+			    &from);
+	if (rc != payload_nob) {
+		kiblnd_pool_free_node(&tx->tx_pool->tpo_pool, &tx->tx_list);
+		return -EFAULT;
+	}
+
 	nob = offsetof(struct kib_immediate_msg, ibim_payload[payload_nob]);
 	kiblnd_init_tx_msg(ni, tx, IBLND_MSG_IMMEDIATE, nob);
 
@@ -1741,8 +1746,14 @@ static int kiblnd_resolve_addr(struct rdma_cm_id *cmid,
 			break;
 		}
 
-		copy_to_iter(&rxmsg->ibm_u.immediate.ibim_payload,
-			     IBLND_MSG_SIZE, to);
+		rc = copy_to_iter(&rxmsg->ibm_u.immediate.ibim_payload, rlen,
+				  to);
+		if (rc != rlen) {
+			rc = -EFAULT;
+			break;
+		}
+
+		rc = 0;
 		lnet_finalize(ni, lntmsg, 0);
 		break;
 
--
1.8.3.1