From 23cba9cbde0bba05d772b335fe5f66aa82b9ad19 Mon Sep 17 00:00:00 2001
From: jiangyiwen <jiangyiwen@huawei.com>
Date: Fri, 3 Aug 2018 12:11:34 +0800
Subject: [PATCH] 9p/virtio: fix off-by-one error in sg list bounds check
Git-commit: 23cba9cbde0bba05d772b335fe5f66aa82b9ad19
Patch-mainline: v4.19-rc1
References: bsc#1051510

Because the value of limit is VIRTQUEUE_NUM, if index is equal to
limit, it will cause sg array out of bounds, so correct the judgement
of BUG_ON.

Link: http://lkml.kernel.org/r/5B63D5F6.6080109@huawei.com
Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jun Piao <piaojun@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/9p/trans_virtio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 6265d1d62749..08264bae3f5d 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -191,7 +191,7 @@ static int pack_sg_list(struct scatterlist *sg, int start,
 		s = rest_of_page(data);
 		if (s > count)
 			s = count;
-		BUG_ON(index > limit);
+		BUG_ON(index >= limit);
 		/* Make sure we don't terminate early. */
 		sg_unmark_end(&sg[index]);
 		sg_set_buf(&sg[index++], data, s);
@@ -236,6 +236,7 @@ pack_sg_list_p(struct scatterlist *sg, int start, int limit,
 		s = PAGE_SIZE - data_off;
 		if (s > count)
 			s = count;
+		BUG_ON(index >= limit);
 		/* Make sure we don't terminate early. */
 		sg_unmark_end(&sg[index]);
 		sg_set_page(&sg[index++], pdata[i++], s, data_off);
-- 
2.18.0