CVE-2026-46132

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo<br /> <br /> rtnl_fill_vfinfo() declares struct ifla_vf_broadcast on the stack<br /> without initialisation:<br /> <br /> struct ifla_vf_broadcast vf_broadcast;<br /> <br /> The struct contains a single fixed 32-byte field:<br /> <br /> /* include/uapi/linux/if_link.h */<br /> struct ifla_vf_broadcast {<br /> __u8 broadcast[32];<br /> };<br /> <br /> The function then copies dev-&gt;broadcast into it using dev-&gt;addr_len<br /> as the length:<br /> <br /> memcpy(vf_broadcast.broadcast, dev-&gt;broadcast, dev-&gt;addr_len);<br /> <br /> On Ethernet devices (the overwhelming majority of SR-IOV NICs)<br /> dev-&gt;addr_len is 6, so only the first 6 bytes of broadcast[] are<br /> written. The remaining 26 bytes retain whatever was previously on<br /> the kernel stack. The full struct is then handed to userspace via:<br /> <br /> nla_put(skb, IFLA_VF_BROADCAST,<br /> sizeof(vf_broadcast), &amp;vf_broadcast)<br /> <br /> leaking up to 26 bytes of uninitialised kernel stack per VF per<br /> RTM_GETLINK request, repeatable.<br /> <br /> The other vf_* structs in the same function are explicitly zeroed<br /> for exactly this reason - see the memset() calls for ivi,<br /> vf_vlan_info, node_guid and port_guid a few lines above.<br /> vf_broadcast was simply missed when it was added.<br /> <br /> Reachability: any unprivileged local process can open AF_NETLINK /<br /> NETLINK_ROUTE without capabilities and send RTM_GETLINK with an<br /> IFLA_EXT_MASK attribute carrying RTEXT_FILTER_VF. The kernel walks<br /> each VF and emits IFLA_VF_BROADCAST, leaking 26 bytes of stack per<br /> VF per request. Stack residue at this call site can include return<br /> addresses and transient sensitive data; KASAN with stack<br /> instrumentation, or KMSAN, will flag the nla_put() when reproduced.<br /> <br /> Zero the on-stack struct before the partial memcpy, matching the<br /> existing pattern used for the other vf_* structs in the same<br /> function.