CVE-2026-68138 — net/sched: serialize qdisc_rtab_list against concurrent get/put

Affected: Linux

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

net/sched: serialize qdisc_rtab_list against concurrent get/put

qdisc_get_rtab() and qdisc_put_rtab() mutate the process-global singly linked list qdisc_rtab_list and a plain non-atomic 'int refcnt' with no lock. This was only safe because every caller historically held the RTNL mutex, which serialized all rate-table lookups, inserts and frees.

That invariant no longer holds. cls_flower sets TCF_PROTO_OPS_DOIT_UNLOCKED, so tc_new_tfilter() keeps rtnl_held == false for it and sets TCA_ACT_FLAGS_NO_RTNL. That flag propagates through tcf_exts_validate_ex() -> tcf_action_init() -> tcf_action_init_1() -> tcf_police_init(), which calls qdisc_get_rtab()/qdisc_put_rtab() with the RTNL mutex NOT held. Two RTM_NEWTFILTER requests on different CPUs, each adding a flower filter with a police action carrying the same rate, then race on qdisc_rtab_list and on the non-atomic refcnt, leading to a use-after-free / double-free of the kmalloc-2k struct qdisc_rate_table. qdisc_rtab_list is a single global (not per-netns), so the corrupted object is shared system-wide.

BUG: KASAN: slab-use-after-free in qdisc_put_rtab+0x12f/0x160 qdisc_put_rtab+0x12f/0x160 tcf_police_init+0xda9/0x1590 tcf_action_init_1+0x460/0x6b0 tcf_action_init+0x439/0xa40 tcf_exts_validate_ex+0x42d/0x550 fl_change+0xddd/0x7da0 tc_new_tfilter+0xaa7/0x2420 rtnetlink_rcv_msg+0x95e/0xe90 which belongs to the cache kmalloc-2k of siz…

USN-8781-1 — linux-nvidia-tegra vulnerabilities

Affected: Ubuntu:24.04:LTS: linux-nvidia-tegra

It was discovered that some Arm processors could complete a broadcast translation lookaside buffer (TLB) invalidation before memory writes made through the invalidated translation were globally observed. A local attacker could possibly use this to write to memory after permission to do so had been revoked, bypassing memory protections or escalating privileges. (CVE-2025-10263)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - User-space API (UAPI); - Kernel build system; - ARM32 architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - User-Mode Linux (UML); - x86 architecture; - Cryptographic API; - Intel NPU Driver; - Compute Acceleration Framework; - ACPI drivers; - Drivers core; - DRBD Distributed Replicated Block Device drivers; - Rados block device (RBD) driver; - Ublk userspace block driver; - Compressed RAM block device driver; - Bluetooth drivers; - Hardware crypto device drivers; - CXL (Compute Express Link) drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - FPGA Framework; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - I3C subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Multiple devices driver; - Media…

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CVE-2026-68138 — net/sched: serialize qdisc_rtab_list against concurrent get/put

USN-8781-1 — linux-nvidia-tegra vulnerabilities