CVE-2026-68288net: drop_monitor: fix info leak in NET_DM_ATTR_PAYLOAD

Official description

In the Linux kernel, the following vulnerability has been resolved: net: drop_monitor: fix info leak in NET_DM_ATTR_PAYLOAD net_dm_packet_report_fill() and net_dm_hw_packet_report_fill() open code the NET_DM_ATTR_PAYLOAD attribute to avoid zeroing the packet payload before overwriting it with skb_copy_bits(). skb_put() reserves nla_total_size(payload_len), i.e. the header plus the NLA_ALIGN() padding, but only payload_len bytes are copied in. When payload_len is not a multiple of 4 the 1-3 padding bytes are never initialized and are leaked to user space inside the netlink message. KMSAN confirms the leak for the software path when the packet payload length is not 4-byte aligned: BUG: KMSAN: kernel-infoleak in _copy_to_iter _copy_to_iter __skb_datagram_iter skb_copy_datagram_iter netlink_recvmsg sock_recvmsg __sys_recvfrom Uninit was created at: kmem_cache_alloc_node_noprof __alloc_skb net_dm_packet_work Bytes 173-175 of 176 are uninitialized Use __nla_reserve(), which sets up the attribute header and zeroes the padding, instead of open coding the attribute construction.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/d427b152b663cb2b19fcd449d792e17edbe4a938
• https://git.kernel.org/stable/c/3c0bc7dcc5f9257d25c59eeb7ccb4df33dcfc446
• https://git.kernel.org/stable/c/05173de42a9923a3eaadebcb0dd5bc83ffba174c
• https://git.kernel.org/stable/c/89178ffe5bddc99c057ba2768db1f8d9c5e1408c
• https://git.kernel.org/stable/c/8fd6975d2aecc36b25ee82b6aef88e62a3527ccb
• https://git.kernel.org/stable/c/5e9c8baee0329fbefe7c67aea945e2a07f15e98b