On 2019/9/23 下午5:12, wangxu (AE) wrote:
Hi Michael
Thanks for your fast reply.
As the following code, the 2nd branch of iov_iter_advance() does not check if i->count < size, when this happens, i->count -= size may cause len exceed INT_MAX, and then total_len exceed INT_MAX.
handle_tx_copy() ->
get_tx_bufs(..., &len, ...) ->
init_iov_iter() ->
iov_iter_advance(iter, ...) // has 3 branches:
pipe_advance() // has checked the size: if (unlikely(i->count < size)) size = i->count;
iov_iter_is_discard() ... // no check.
Yes, but I don't think we use ITER_DISCARD.
Thanks
iterate_and_advance() //has checked: if (unlikely(i->count < n)) n = i->count;
return iov_iter_count(iter);
-----Original Message-----
From: Michael S. Tsirkin [mailto:mst@xxxxxxxxxx]
Sent: Monday, September 23, 2019 4:07 PM
To: wangxu (AE) <wangxu72@xxxxxxxxxx>
Cc: jasowang@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] vhost: It's better to use size_t for the 3rd parameter of vhost_exceeds_weight()
On Mon, Sep 23, 2019 at 03:46:41PM +0800, wangxu wrote:
From: Wang Xu <wangxu72@xxxxxxxxxx>
Caller of vhost_exceeds_weight(..., total_len) in drivers/vhost/net.c
usually pass size_t total_len, which may be affected by rx/tx package.
Signed-off-by: Wang Xu <wangxu72@xxxxxxxxxx>
Puts a bit more pressure on the register file ...
why do we care? Is there some way that it can exceed INT_MAX?
---
drivers/vhost/vhost.c | 4 ++--
drivers/vhost/vhost.h | 7 ++++---
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index
36ca2cf..159223a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -412,7 +412,7 @@ static void vhost_dev_free_iovecs(struct vhost_dev
*dev) }
bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
- int pkts, int total_len)
+ int pkts, size_t total_len)
{
struct vhost_dev *dev = vq->dev;
@@ -454,7 +454,7 @@ static size_t vhost_get_desc_size(struct
vhost_virtqueue *vq,
void vhost_dev_init(struct vhost_dev *dev,
struct vhost_virtqueue **vqs, int nvqs,
- int iov_limit, int weight, int byte_weight)
+ int iov_limit, int weight, size_t byte_weight)
{
struct vhost_virtqueue *vq;
int i;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index
e9ed272..8d80389d 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -172,12 +172,13 @@ struct vhost_dev {
wait_queue_head_t wait;
int iov_limit;
int weight;
- int byte_weight;
+ size_t byte_weight;
};
This just costs extra memory, and value is never large, so I don't think this matters.
-bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int
total_len);
+bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts,
+ size_t total_len);
void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
- int nvqs, int iov_limit, int weight, int byte_weight);
+ int nvqs, int iov_limit, int weight, size_t byte_weight);
long vhost_dev_set_owner(struct vhost_dev *dev); bool
vhost_dev_has_owner(struct vhost_dev *dev); long
vhost_dev_check_owner(struct vhost_dev *);
--
1.8.5.6
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