提交 0dd34404 编写于 作者: N Neeraj Upadhyay 提交者: Zheng Zengkai

vringh: Use wiov->used to check for read/write desc order

mainline inclusion
from mainline-5.10.62
commit c7ee4d22614e43ae1d633864b70ac075469ad27f
bugzilla: 182217 https://gitee.com/openeuler/kernel/issues/I4EFOS

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c7ee4d22614e43ae1d633864b70ac075469ad27f

--------------------------------

[ Upstream commit e74cfa91 ]

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: NJason Wang <jasowang@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NNeeraj Upadhyay <neeraju@codeaurora.org>
Link: https://lore.kernel.org/r/1624591502-4827-1-git-send-email-neeraju@codeaurora.orgSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
上级 f5c79108
......@@ -341,7 +341,7 @@ __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;
......
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