CVE-2021-47127

Summary

CVE-2021-47127 is a vulnerability affecting the Linux kernel that was introduced by the commit c7a219048e45 in the ice driver. This commit silently removed the xsk_buff_pool from the VSI structure, leading to the Tx side of AF_XDP being broken in copy mode. Consequently, when xdpsock is run in txonly or l2fwd scenarios, a NULL pointer dereference occurs, resulting in a kernel panic. The issue can be resolved by implementing a bitmap of queues that are zero-copy enabled, allowing each bit to represent a queue ID that xsk pool is configured on. This bitmap will be used in ice_xsk_pool({en,dis}able) and checked in ice_xsk_pool() to determine which napi poll routine is executed. This solution is inspired by other drivers such as i40e and ixgbe.

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