Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: net: guard timestamp cmsgs to real error queue skbs skb_is_err_queue() treats PACKET_OUTGOING as the sole marker for an skb from sk_error_queue. That assumption is not true for AF_PACKET sockets: outgoing packet taps are also delivered to packet sockets with skb->pkt_type == PACKET_OUTGOING, but their skb->cb is owned by AF_PACKET instead of struct sock_exterr_skb. If such an skb is received with timestamping enabled, the generic timestamp cmsg path can read AF_PACKET control-buffer state as sock_exterr_skb::opt_stats. With SO_RXQ_OVFL enabled, the packet drop counter overlaps opt_stats. An odd drop count makes the path emit SCM_TIMESTAMPING_OPT_STATS with skb->len and skb->data. For non-linear skbs this copies past the linear head and can trigger hardened usercopy or disclose adjacent heap contents. Keep skb_is_err_queue() local to net/socket.c, but make it verify that the PACKET_OUTGOING marker is paired with the sock_rmem_free destructor installed by sock_queue_err_skb(). AF_PACKET receive skbs use normal receive ownership and no longer pass as error-queue skbs, while legitimate sk_error_queue entries keep the PACKET_OUTGOING marker and sock_rmem_free ownership.

Affected versions

Linux: 8605330aac5a5785630aec8f64378a54891937cc through before 24a0d548d3a765cd4558224e4f8e06e14cba26e3 (git); 8605330aac5a5785630aec8f64378a54891937cc through before 71ff5cdd5da61d0438e902aa0fd68c28bc901abe (git); 8605330aac5a5785630aec8f64378a54891937cc through before ad9a0374ee6d11048e1f74cd5180bad58b9848b4 (git); 8605330aac5a5785630aec8f64378a54891937cc through before b903e9b5629ec8dd6db92174070045bf81ad7060 (git); 8605330aac5a5785630aec8f64378a54891937cc through before e0665b2a8e90bb08bd205062c75662b502d31797 (git); 8605330aac5a5785630aec8f64378a54891937cc through before 3dde4fb941fa5649ab809f6cd3e20e0c424a4e31 (git); 8605330aac5a5785630aec8f64378a54891937cc through before eb51a9ad3ceb01bc6c0fb608dbc856e03ee6f24a (git); 8605330aac5a5785630aec8f64378a54891937cc through before 1ee90b77b727df903033db873c75caac5c27ec98 (git); cdaf15b43bd31003220cb080bcbbd57787a2fca9 (git); 4.10.14 through before 4.11 (semver); 4.11; V3.1.6 through before * (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.