{"id":"CVE-2026-99282","published":"2026-11-07T14:17:03.940","lastModified":"2026-11-10T19:22:31.583","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_teql: fix use-after-free on lower qdisc drop\n\nThe issue: teql_master_xmit() tests the slave's ndo_start_xmit() return\nvalue against NETDEV_TX_OK alone. A slave that consumes the skb but\nreturns an error code (rc < NET_XMIT_MASK, e.g. NET_XMIT_DROP) is treated\nas if the skb were still owned, so the loop restores skb->dev and calls\n__skb_pull() on it. A VLAN slave returns the result of dev_queue_xmit()\nfrom its ndo_start_xmit() (propagated since cbbef5e18307), and when the\nlower qdisc drops the packet that value is NET_XMIT_DROP after the skb\nhas been freed, giving a use-after-free in teql_master_xmit().\n\nThe Fix: test for consumption with dev_xmit_complete(), which accepts\nNETDEV_TX_OK and every rc < NET_XMIT_MASK, matching other callers that\nneed to distinguish consumed results from busy. Only NETDEV_TX_OK keeps\nthe packet counted in tx_packets/tx_bytes and advances the slave; a\nconsumed result that is neither a success nor NET_XMIT_CN ends the\nattempt and is charged to tx_dropped, so lower-qdisc drops are no longer\nreported as good transmits. NET_XMIT_CN is counted like success because\nit can accompany acceptance of the current packet: pfifo_head_drop drops\nthe old head, enqueues the current skb and returns NET_XMIT_CN.\n\nConditions to recreate the bug:\nWith CONFIG_NET_SCH_TEQL,\nCONFIG_VLAN_8021Q and CONFIG_DUMMY enabled, add lkrdummy0 (dummy) and\nlkrvlan0 (VLAN id 37 on lkrdummy0); set a pfifo limit 0 root on lkrdummy0\nand a teql0 root on lkrvlan0; bring teql0 up with an address and send one\nUDP packet to it. The VLAN xmit returns NET_XMIT_DROP from the lower\nqdisc while holding a freed skb.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/2702ae318630787c640ec0d0403ffd9d95c43e9e","tags":[]},{"url":"https://git.kernel.org/stable/c/782d6bb8f9b8e9d8591181662222bf74cd3ecf79","tags":[]},{"url":"https://git.kernel.org/stable/c/8d5f768780e26cb82c389219ae7fdb1cd7255421","tags":[]},{"url":"https://git.kernel.org/stable/c/fc55d92ae6a4b2e7d062cad6d4c67f6b061d9cde","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}