From: Xie Yongji xieyongji@bytedance.com
[ Upstream commit dbd29e0752286af74243cf891accf472b2f3edd8 ]
We should use size of descriptor chain to test loop condition in the indirect case. And another statistical count is also introduced for indirect descriptors to avoid conflict with the statistical count of direct descriptors.
Fixes: f87d0fbb5798 ("vringh: host-side implementation of virtio rings.") Signed-off-by: Xie Yongji xieyongji@bytedance.com Signed-off-by: Fam Zheng fam.zheng@bytedance.com Message-Id: 20220505100910.137-1-xieyongji@bytedance.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Acked-by: Jason Wang jasowang@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/vhost/vringh.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c index da47542496cc..63f0ab3e6f63 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -262,7 +262,7 @@ __vringh_iov(struct vringh *vrh, u16 i, gfp_t gfp, int (*copy)(void *dst, const void *src, size_t len)) { - int err, count = 0, up_next, desc_max; + int err, count = 0, indirect_count = 0, up_next, desc_max; struct vring_desc desc, *descs; struct vringh_range range = { -1ULL, 0 }, slowrange; bool slow = false; @@ -319,7 +319,12 @@ __vringh_iov(struct vringh *vrh, u16 i, continue; }
- if (count++ == vrh->vring.num) { + if (up_next == -1) + count++; + else + indirect_count++; + + if (count > vrh->vring.num || indirect_count > desc_max) { vringh_bad("Descriptor loop in %p", descs); err = -ELOOP; goto fail; @@ -381,6 +386,7 @@ __vringh_iov(struct vringh *vrh, u16 i, i = return_from_indirect(vrh, &up_next, &descs, &desc_max); slow = false; + indirect_count = 0; } else break; }