CVE-2025-68325

Summary

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

net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop

In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen and backlog of the qdisc hierarchy. Its caller, cake_enqueue(), assumes that the parent qdisc will enqueue the current packet. However, this assumption breaks when cake_enqueue() returns NET_XMIT_CN: the parent qdisc stops enqueuing current packet, leaving the tree qlen/backlog accounting inconsistent. This mismatch can lead to a NULL dereference (e.g., when the parent Qdisc is qfq_qdisc).

This patch computes the qlen/backlog delta in a more robust way by observing the difference before and after the series of cake_drop() calls, and then compensates the qdisc tree accounting if cake_enqueue() returns NET_XMIT_CN.

To ensure correct compensation when ACK thinning is enabled, a new variable is introduced to keep qlen unchanged.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxde04ddd2980b48caa8d7e24a7db2742917a8b280 < a3f4e3de41a3f115db35276c6b186ccbc913934aaffected
LinuxLinux0dacfc5372e314d1219f03e64dde3ab495a5a25e < 38abf6e931b169ea88d7529b49096f53a5dcf8feaffected
LinuxLinux710866fc0a64eafcb8bacd91bcb1329eb7e5035f < fcb91be52eb6e92e00b533ebd7c77fecada537e1affected
LinuxLinuxaa12ee1c1bd260943fd6ab556d8635811c332eeb < d01f0e072dadb02fe10f436b940dd957aff0d7d4affected
LinuxLinuxff57186b2cc39766672c4c0332323933e5faaa88 < 0b6216f9b3d1c33c76f74511026e5de5385ee520affected
LinuxLinux15de71d06a400f7fdc15bf377a2552b0ec437cf5 < 529c284cc2815c8350860e9a31722050fe7117cbaffected
LinuxLinux15de71d06a400f7fdc15bf377a2552b0ec437cf5 < 3ed6c458530a547ed0c9ea0b02b19bab620be88baffected
LinuxLinux15de71d06a400f7fdc15bf377a2552b0ec437cf5 < 9fefc78f7f02d71810776fdeb119a05a946a27ccaffected
LinuxLinux7689ab22de36f8db19095f6bdf11f28cfde92f5caffected
LinuxLinux62d591dde4defb1333d202410609c4ddeae060b3affected
LinuxLinux5.10.241 < 5.10.248affected
LinuxLinux5.15.190 < 5.15.198affected
LinuxLinux6.1.149 < 6.1.160affected
LinuxLinux6.6.103 < 6.6.120affected
LinuxLinux6.12.44 < 6.12.63affected
LinuxLinux5.4.297 < 5.5affected
LinuxLinux6.16.4 < 6.17affected
LinuxLinux6.17affected
LinuxLinux0 < 6.17unaffected
LinuxLinux5.10.248 <= 5.10.*unaffected
LinuxLinux5.15.198 <= 5.15.*unaffected
LinuxLinux6.1.160 <= 6.1.*unaffected
LinuxLinux6.6.120 <= 6.6.*unaffected
LinuxLinux6.12.63 <= 6.12.*unaffected
LinuxLinux6.17.13 <= 6.17.*unaffected
LinuxLinux6.18.2 <= 6.18.*unaffected
LinuxLinux6.19 <= *unaffected

Weaknesses

References