Description
In the Linux kernel, the following vulnerability has been resolved: net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo rtnl_fill_vfinfo() declares struct ifla_vf_broadcast on the stack without initialisation: struct ifla_vf_broadcast vf_broadcast; The struct contains a single fixed 32-byte field: /* include/uapi/linux/if_link.h */ struct ifla_vf_broadcast { __u8 broadcast[32]; }; The function then copies dev->broadcast into it using dev->addr_len as the length: memcpy(vf_broadcast.broadcast, dev->broadcast, dev->addr_len); On Ethernet devices (the overwhelming majority of SR-IOV NICs) dev->addr_len is 6, so only the first 6 bytes of broadcast[] are written. The remaining 26 bytes retain whatever was previously on the kernel stack. The full struct is then handed to userspace via: nla_put(skb, IFLA_VF_BROADCAST, sizeof(vf_broadcast), &vf_broadcast) leaking up to 26 bytes of uninitialised kernel stack per VF per RTM_GETLINK request, repeatable. The other vf_* structs in the same function are explicitly zeroed for exactly this reason - see the memset() calls for ivi, vf_vlan_info, node_guid and port_guid a few lines above. vf_broadcast was simply missed when it was added. Reachability: any unprivileged local process can open AF_NETLINK / NETLINK_ROUTE without capabilities and send RTM_GETLINK with an IFLA_EXT_MASK attribute carrying RTEXT_FILTER_VF. The kernel walks each VF and emits IFLA_VF_BROADCAST, leaking 26 bytes of stack per VF per request. Stack residue at this call site can include return addresses and transient sensitive data; KASAN with stack instrumentation, or KMSAN, will flag the nla_put() when reproduced. Zero the on-stack struct before the partial memcpy, matching the existing pattern used for the other vf_* structs in the same function.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
75345f888f700c4ab2448287e35d48c760b202e6 to < 14271b401ec6a4bf0d88054106fc2956084717e1affected75345f888f700c4ab2448287e35d48c760b202e6 to < cccce3190ba4356432b9f22369b56123d3d89f0daffected75345f888f700c4ab2448287e35d48c760b202e6 to < a44fbb631cba646532f3948636626f81717365a7affected75345f888f700c4ab2448287e35d48c760b202e6 to < 0653c0516234c8258975d268a749115fc0f0ff00affected75345f888f700c4ab2448287e35d48c760b202e6 to < c5b1b92ab7eff1a6e8c507ddde6fd02fabd0cfa8affected75345f888f700c4ab2448287e35d48c760b202e6 to < fbe0e6197225e6a83cf113a67a4b425f8de0bcd5affected75345f888f700c4ab2448287e35d48c760b202e6 to < 38bcc21f52246badb3154b6158dcb381d98de011affected75345f888f700c4ab2448287e35d48c760b202e6 to < 4b9e327991815e128ad3af75c3a04630a63ce3e0affected
Linux Linux
Default version status: affected
5.3affected0 to < 5.3unaffected5.10.258 to ≤ 5.10.*unaffected5.15.209 to ≤ 5.15.*unaffected6.1.175 to ≤ 6.1.*unaffected6.6.140 to ≤ 6.6.*unaffected6.12.88 to ≤ 6.12.*unaffected6.18.30 to ≤ 6.18.*unaffected7.0.7 to ≤ 7.0.*unaffected7.1 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/14271b401ec6a4bf0d88054106fc2956084717e1 ↗
- https://git.kernel.org/stable/c/cccce3190ba4356432b9f22369b56123d3d89f0d ↗
- https://git.kernel.org/stable/c/a44fbb631cba646532f3948636626f81717365a7 ↗
- https://git.kernel.org/stable/c/0653c0516234c8258975d268a749115fc0f0ff00 ↗
- https://git.kernel.org/stable/c/c5b1b92ab7eff1a6e8c507ddde6fd02fabd0cfa8 ↗
- https://git.kernel.org/stable/c/fbe0e6197225e6a83cf113a67a4b425f8de0bcd5 ↗
- https://git.kernel.org/stable/c/38bcc21f52246badb3154b6158dcb381d98de011 ↗
- https://git.kernel.org/stable/c/4b9e327991815e128ad3af75c3a04630a63ce3e0 ↗
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html ↗