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[SRU,J/L/M,1/1] vringh: don't use vringh_kiov_advance() in vringh_iov_xfer()

Message ID 20231026195451.32587-2-yuxuan.luo@canonical.com
State New
Headers show
Series [SRU,J/L/M,1/1] vringh: don't use vringh_kiov_advance() in vringh_iov_xfer() | expand

Commit Message

Yuxuan Luo Oct. 26, 2023, 7:54 p.m. UTC 
From: Stefano Garzarella <sgarzare@redhat.com>

In the while loop of vringh_iov_xfer(), `partlen` could be 0 if one of
the `iov` has 0 lenght.
In this case, we should skip the iov and go to the next one.
But calling vringh_kiov_advance() with 0 lenght does not cause the
advancement, since it returns immediately if asked to advance by 0 bytes.

Let's restore the code that was there before commit b8c06ad4d67d
("vringh: implement vringh_kiov_advance()"), avoiding using
vringh_kiov_advance().

Fixes: b8c06ad4d67d ("vringh: implement vringh_kiov_advance()")
Cc: stable@vger.kernel.org
Reported-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 7aed44babc7f97e82b38e9a68515e699692cc100)
CVE-2023-5158
Signed-off-by: Yuxuan Luo <yuxuan.luo@canonical.com>
---
 drivers/vhost/vringh.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 786876af0a73a..13b75213ebaae 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -123,8 +123,18 @@  static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
 		done += partlen;
 		len -= partlen;
 		ptr += partlen;
+		iov->consumed += partlen;
+		iov->iov[iov->i].iov_len -= partlen;
+		iov->iov[iov->i].iov_base += partlen;
 
-		vringh_kiov_advance(iov, partlen);
+		if (!iov->iov[iov->i].iov_len) {
+			/* Fix up old iov element then increment. */
+			iov->iov[iov->i].iov_len = iov->consumed;
+			iov->iov[iov->i].iov_base -= iov->consumed;
+
+			iov->consumed = 0;
+			iov->i++;
+		}
 	}
 	return done;
 }