From: Sagi Grimberg <sagi@grimberg.me>
Date: Wed, 13 Jan 2021 13:56:57 -0800
Subject: [PATCH] nvme-tcp: fix possible data corruption with bio merges
Git-commit: ca1ff67d0fb14f39cf0cc5102b1fbcc3b14f6fb9
Patch-mainline: v5.11-rc1
References: git-fixes

When a bio merges, we can get a request that spans multiple
bios, and the overall request payload size is the sum of
all bios. When we calculate how much we need to send
from the existing bio (and bvec), we did not take into
account the iov_iter byte count cap.

Since multipage bvecs support, bvecs can split in the middle
which means that when we account for the last bvec send we
should also take the iov_iter byte count cap as it might be
lower than the last bvec size.

Reported-by: Hao Wang <pkuwangh@gmail.com>
Fixes: 3f2304f8c6d6 ("nvme-tcp: add NVMe over TCP host driver")
Tested-by: Hao Wang <pkuwangh@gmail.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/nvme/host/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index b2e0865785ef..216619926563 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -201,7 +201,7 @@ static inline size_t nvme_tcp_req_cur_offset(struct nvme_tcp_request *req)
 
 static inline size_t nvme_tcp_req_cur_length(struct nvme_tcp_request *req)
 {
-	return min_t(size_t, req->iter.bvec->bv_len - req->iter.iov_offset,
+	return min_t(size_t, iov_iter_single_seg_count(&req->iter),
 			req->pdu_len - req->pdu_sent);
 }
 
-- 
2.29.2