On Fri, Apr 23, 2021 at 12:33:09PM +0800, Jason Wang wrote:
>
> 在 2021/4/23 下午12:19, Xuan Zhuo 写道:
> > On Fri, 23 Apr 2021 12:08:34 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> > > 在 2021/4/22 下午11:16, Xuan Zhuo 写道:
> > > > When "headroom" > 0, the actual allocated memory space is the entire
> > > > page, so the address of the page should be used when passing it to
> > > > build_skb().
> > > >
> > > > BUG: KASAN: use-after-free in skb_gro_receive (net/core/skbuff.c:4260)
> > > > Write of size 16 at addr ffff88811619fffc by task kworker/u9:0/534
> > > > CPU: 2 PID: 534 Comm: kworker/u9:0 Not tainted 5.12.0-rc7-custom-16372-gb150be05b806 #3382
> > > > Hardware name: QEMU MSN2700, BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
> > > > Workqueue: xprtiod xs_stream_data_receive_workfn [sunrpc]
> > > > Call Trace:
> > > > <IRQ>
> > > > dump_stack (lib/dump_stack.c:122)
> > > > print_address_description.constprop.0 (mm/kasan/report.c:233)
> > > > kasan_report.cold (mm/kasan/report.c:400 mm/kasan/report.c:416)
> > > > skb_gro_receive (net/core/skbuff.c:4260)
> > > > tcp_gro_receive (net/ipv4/tcp_offload.c:266 (discriminator 1))
> > > > tcp4_gro_receive (net/ipv4/tcp_offload.c:316)
> > > > inet_gro_receive (net/ipv4/af_inet.c:1545 (discriminator 2))
> > > > dev_gro_receive (net/core/dev.c:6075)
> > > > napi_gro_receive (net/core/dev.c:6168 net/core/dev.c:6198)
> > > > receive_buf (drivers/net/virtio_net.c:1151) virtio_net
> > > > virtnet_poll (drivers/net/virtio_net.c:1415 drivers/net/virtio_net.c:1519) virtio_net
> > > > __napi_poll (net/core/dev.c:6964)
> > > > net_rx_action (net/core/dev.c:7033 net/core/dev.c:7118)
> > > > __do_softirq (./arch/x86/include/asm/jump_label.h:25 ./include/linux/jump_label.h:200 ./include/trace/events/irq.h:142 kernel/softirq.c:346)
> > > > irq_exit_rcu (kernel/softirq.c:221 kernel/softirq.c:422 kernel/softirq.c:434)
> > > > common_interrupt (arch/x86/kernel/irq.c:240 (discriminator 14))
> > > > </IRQ>
> > > >
> > > > Fixes: fb32856b16ad ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom")
> > > > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > > > Reported-by: Ido Schimmel <idosch@xxxxxxxxxx>
> > > > Tested-by: Ido Schimmel <idosch@xxxxxxxxxx>
> > > > ---
> > >
> > > Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> > >
> > > The codes became hard to read, I think we can try to do some cleanups on
> > > top to make it easier to read.
> > >
> > > Thanks
> > Yes, this piece of code needs to be sorted out. Especially the big and mergeable
> > scenarios should be handled separately. Remove the mergeable code from this
> > function, and mergeable uses a new function alone.
>
>
> Right, another thing is that we may consider to relax the checking of len <
> GOOD_COPY_LEN.
Want to post a patch on top?
> Our QE still see low PPS compared with the code before 3226b158e67c ("net:
> avoid 32 x truesize under-estimation for tiny skbs").
>
> Thanks
>
>
> >
> > Thanks.
> >
> > >
> > > > drivers/net/virtio_net.c | 12 +++++++++---
> > > > 1 file changed, 9 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > > index 74d2d49264f3..7fda2ae4c40f 100644
> > > > --- a/drivers/net/virtio_net.c
> > > > +++ b/drivers/net/virtio_net.c
> > > > @@ -387,7 +387,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > > unsigned int copy, hdr_len, hdr_padded_len;
> > > > struct page *page_to_free = NULL;
> > > > int tailroom, shinfo_size;
> > > > - char *p, *hdr_p;
> > > > + char *p, *hdr_p, *buf;
> > > >
> > > > p = page_address(page) + offset;
> > > > hdr_p = p;
> > > > @@ -403,11 +403,15 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > > * space are aligned.
> > > > */
> > > > if (headroom) {
> > > > - /* The actual allocated space size is PAGE_SIZE. */
> > > > + /* Buffers with headroom use PAGE_SIZE as alloc size,
> > > > + * see add_recvbuf_mergeable() + get_mergeable_buf_len()
> > > > + */
> > > > truesize = PAGE_SIZE;
> > > > tailroom = truesize - len - offset;
> > > > + buf = page_address(page);
> > > > } else {
> > > > tailroom = truesize - len;
> > > > + buf = p;
> > > > }
> > > >
> > > > len -= hdr_len;
> > > > @@ -416,11 +420,13 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > >
> > > > shinfo_size = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
> > > >
> > > > + /* copy small packet so we can reuse these pages */
> > > > if (!NET_IP_ALIGN && len > GOOD_COPY_LEN && tailroom >= shinfo_size) {
> > > > - skb = build_skb(p, truesize);
> > > > + skb = build_skb(buf, truesize);
> > > > if (unlikely(!skb))
> > > > return NULL;
> > > >
> > > > + skb_reserve(skb, p - buf);
> > > > skb_put(skb, len);
> > > > goto ok;
> > > > }
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
