On 4/25/22 12:37 PM, Nikolay Aleksandrov wrote:
We received a report[1] of kernel crashes when Cilium is used in XDP
mode with virtio_net after updating to newer kernels. After
investigating the reason it turned out that when using mergeable bufs
with an XDP program which adjusts xdp.data or xdp.data_meta page_to_buf()
calculates the build_skb address wrong because the offset can become less
than the headroom so it gets the address of the previous page (-X bytes
depending on how lower offset is):
page_to_skb: page addr ffff9eb2923e2000 buf ffff9eb2923e1ffc offset 252 headroom 256
[...]
CC: stable@xxxxxxxxxxxxxxx
CC: Jason Wang <jasowang@xxxxxxxxxx>
CC: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
CC: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
CC: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
CC: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 8fb7da9e9907 ("virtio_net: get build_skb() buf by data ptr")
Signed-off-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
Thanks everyone!
Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
