CVE-2022-49872

/// Technical description

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

net: gso: fix panic on frag_list with mixed head alloc types

Since commit 3dcbdb134f32 ("net: gso: Fix skb_segment splat when

splitting gso_size mangled skb having linear-headed frag_list"), it is

allowed to change gso_size of a GRO packet. However, that commit assumes

that "checking the first list_skb member suffices; i.e if either of the

list_skb members have non head_frag head, then the first one has too".

It turns out this assumption does not hold. We've seen BUG_ON being hit

in skb_segment when skbs on the frag_list had differing head_frag with

the vmxnet3 driver. This happens because __netdev_alloc_skb and

__napi_alloc_skb can return a skb that is page backed or kmalloced

depending on the requested size. As the result, the last small skb in

the GRO packet can be kmalloced.

There are three different locations where this can be fixed:

(1) We could check head_frag in GRO and not allow GROing skbs with

diffe

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References