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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Jason Wang <jasowang@redhat.com>,
	Stefano Garzarella <sgarzare@redhat.com>,
	Neeraj Upadhyay <neeraju@codeaurora.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 15/23] vringh: Use wiov->used to check for read/write desc order
Date: Wed,  1 Sep 2021 14:27:00 +0200	[thread overview]
Message-ID: <20210901122250.280934988@linuxfoundation.org> (raw)
In-Reply-To: <20210901122249.786673285@linuxfoundation.org>

From: Neeraj Upadhyay <neeraju@codeaurora.org>

[ Upstream commit e74cfa91f42c50f7f649b0eca46aa049754ccdbd ]

As __vringh_iov() traverses a descriptor chain, it populates
each descriptor entry into either read or write vring iov
and increments that iov's ->used member. So, as we iterate
over a descriptor chain, at any point, (riov/wriov)->used
value gives the number of descriptor enteries available,
which are to be read or written by the device. As all read
iovs must precede the write iovs, wiov->used should be zero
when we are traversing a read descriptor. Current code checks
for wiov->i, to figure out whether any previous entry in the
current descriptor chain was a write descriptor. However,
iov->i is only incremented, when these vring iovs are consumed,
at a later point, and remain 0 in __vringh_iov(). So, correct
the check for read and write descriptor order, to use
wiov->used.

Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Link: https://lore.kernel.org/r/1624591502-4827-1-git-send-email-neeraju@codeaurora.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/vhost/vringh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 1e2e01270be9..c23045aa9873 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -330,7 +330,7 @@ __vringh_iov(struct vringh *vrh, u16 i,
 			iov = wiov;
 		else {
 			iov = riov;
-			if (unlikely(wiov && wiov->i)) {
+			if (unlikely(wiov && wiov->used)) {
 				vringh_bad("Readable desc %p after writable",
 					   &descs[i]);
 				err = -EINVAL;
-- 
2.30.2




  parent reply	other threads:[~2021-09-01 12:28 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 12:26 [PATCH 4.14 00/23] 4.14.246-rc1 review Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 01/23] ARC: Fix CONFIG_STACKDEPOT Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 02/23] can: usb: esd_usb2: esd_usb2_rx_event(): fix the interchange of the CAN RX and TX error counters Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 03/23] Revert "USB: serial: ch341: fix character loss at high transfer rates" Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 04/23] USB: serial: option: add new VID/PID to support Fibocom FG150 Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 05/23] usb: dwc3: gadget: Fix dwc3_calc_trbs_left() Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 06/23] usb: dwc3: gadget: Stop EP0 transfers during pullup disable Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 07/23] IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs() Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 08/23] e1000e: Fix the max snoop/no-snoop latency for 10M Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 09/23] ip_gre: add validation for csum_start Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 10/23] xgene-v2: Fix a resource leak in the error handling path of xge_probe() Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 11/23] net: marvell: fix MVNETA_TX_IN_PRGRS bit number Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 12/23] usb: gadget: u_audio: fix race condition on endpoint stop Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 13/23] opp: remove WARN when no valid OPPs remain Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.14 14/23] virtio: Improve vq->broken access to avoid any compiler optimization Greg Kroah-Hartman
2021-09-01 12:27 ` Greg Kroah-Hartman [this message]
2021-09-01 12:27 ` [PATCH 4.14 16/23] drm: Copy drm_wait_vblank to user before returning Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 17/23] drm/nouveau/disp: power down unused DP links during init Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 18/23] net/rds: dma_map_sg is entitled to merge entries Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 19/23] vt_kdsetmode: extend console locking Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 20/23] fbmem: add margin check to fb_check_caps() Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 21/23] KVM: x86/mmu: Treat NX as used (not reserved) for all !TDP shadow MMUs Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 22/23] KVM: X86: MMU: Use the correct inherited permissions to get shadow page Greg Kroah-Hartman
2021-09-01 12:27 ` [PATCH 4.14 23/23] Revert "floppy: reintroduce O_NDELAY fix" Greg Kroah-Hartman
2021-09-01 19:21 ` [PATCH 4.14 00/23] 4.14.246-rc1 review Jon Hunter
2021-09-01 19:22 ` Jon Hunter
2021-09-02  1:08 ` Samuel Zou
2021-09-02 16:08 ` Naresh Kamboju
2021-09-02 21:50 ` Guenter Roeck

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