ice: fix metadata_dst refcount handling on representor teardown

Overview

In the Linux kernel, the following vulnerability has been resolved:

ice: fix metadata_dst refcount handling on representor teardown

ice_eswitch_release_repr() uses metadata_dst_free() to release the representor's metadata_dst. metadata_dst_free() directly frees the underlying memory without checking the dst_entry refcount.

When ice_eswitch_port_start_xmit() processes a packet, it takes a reference via dst_hold() and attaches the metadata_dst to the skb. If the representor is torn down while packets are still queued on the lower device (e.g. in a qdisc), the metadata_dst is freed while references are still held.

Use dst_release() instead, which correctly decrements the refcount and only frees the object when all references are dropped. The dst subsystem already handles metadata_dst cleanup in dst_destroy() when DST_METADATA is set.

Other drivers sharing this pattern (nfp, airoha, bnxt) already use dst_release() for their metadata_dst lifecycle.

Affected

• Linux >= f5396b8a663f7a78ee5b75a47ee524b40795b265 < 1f263235651775f93c15d90c9f25c3f4a4ef6512
• Linux >= f5396b8a663f7a78ee5b75a47ee524b40795b265 < 6f5544f53f1e58ea8a49fb9f9158d5793b9205b0
• Linux >= f5396b8a663f7a78ee5b75a47ee524b40795b265 < beb05f484a1e4a5a66e3678e4b7f3147f651c080
• Linux >= f5396b8a663f7a78ee5b75a47ee524b40795b265 < 5e4d20db5179e83a4948927bc39e489a9a83256d
• Linux >= f5396b8a663f7a78ee5b75a47ee524b40795b265 < 58858b8f14803a7eeac297b3ce20f3b21bf2ff66
• Linux 5.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.