ipvs: bound LBLCR and LBLC cache growth

Overview

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

ipvs: bound LBLCR and LBLC cache growth

ip_vs_lblcr_new() and ip_vs_lblc_new() create cache entries for every previously unseen destination address. The table max_size only tells the periodic collector to reclaim entries after the cache has already exceeded the limit. It does not reclaim entries that the attacker continues to use.

Reject new cache entries once either table reaches max_size * 3 / 2. The extra headroom lets the periodic collector catch up while the existing scheduler fallback continues to use the selected destination when cache creation fails. New traffic therefore stays serviceable without growing the tables further.

Affected

• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 31028d7b970962fbeda1e9131405c76551094300
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6316d17324bd4ca400c26adb7b656c6e3447c209
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 16c83c047ecfaf226ad81d45d77fa11a3184d0e4
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2a3c3de660f96865f303fd25f1285f2ffbfd521d
• Linux 2.6.12

Remediation

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