CVE-2024-58099

In the Linux kernel, the following vulnerability has been resolved:

vmxnet3: Fix packet corruption in vmxnet3xdpxmit_frame

Andrew and Nikolay reported connectivity issues with Cilium's service load-balancing in case of vmxnet3.

If a BPF program for native XDP adds an encapsulation header such as IPIP and transmits the packet out the same interface, then in case of vmxnet3 a corrupted packet is being sent and subsequently dropped on the path.

vmxnet3xdpxmitframe() which is called e.g. via vmxnet3runxdp() through vmxnet3xdpxmitback() calculates an incorrect DMA address:

page = virttopage(xdpf->data); tbi->dmaaddr = pagepoolgetdmaaddr(page) + VMXNET3XDPHEADROOM; dmasyncsinglefordevice(&adapter->pdev->dev, tbi->dmaaddr, bufsize, DMATO_DEVICE);

The above assumes a fixed offset (VMXNET3XDPHEADROOM), but the XDP BPF program could have moved xdp->data. While the passed bufsize is correct (xdpf->len), the dmaaddr needs to have a dynamic offset which can be calculated as xdpf->data - (void *)xdpf, that is, xdp->data - xdp->datahardstart.