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CVE-2024-56770 — net/sched: netem: account for backlog updates from child qdisc

2026-10-15T01:33:20.373860+00:00

Affected: Linux

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

net/sched: netem: account for backlog updates from child qdisc

In general, 'qlen' of any classful qdisc should keep track of the number of packets that the qdisc itself and all of its children holds. In case of netem, 'qlen' only accounts for the packets in its internal tfifo. When netem is used with a child qdisc, the child qdisc can use 'qdisc_tree_reduce_backlog' to inform its parent, netem, about created or dropped SKBs. This function updates 'qlen' and the backlog statistics of netem, but netem does not account for changes made by a child qdisc. 'qlen' then indicates the wrong number of packets in the tfifo. If a child qdisc creates new SKBs during enqueue and informs its parent about this, netem's 'qlen' value is increased. When netem dequeues the newly created SKBs from the child, the 'qlen' in netem is not updated. If 'qlen' reaches the configured sch->limit, the enqueue function stops working, even though the tfifo is not full.

Reproduce the bug: Ensure that the sender machine has GSO enabled. Configure netem as root qdisc and tbf as its child on the outgoing interface of the machine as follows: $ tc qdisc add dev root handle 1: netem delay 100ms limit 100 $ tc qdisc add dev parent 1:0 tbf rate 50Mbit burst 1542 latency 50ms

Send bulk TCP traffic out via this interface, e.g., by running an iPerf3 client on the machine. Check the qdisc statistics: $ tc -s qdisc show dev

Statist…

USN-7379-1 — linux, linux-aws, linux-azure, linux-gcp, linux-hwe-6.11, linux-oracle, linux-realtime vulnerabilities

2026-10-15T01:33:20.374009+00:00

Affected: Ubuntu:24.04:LTS: linux-hwe-6.11

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; - MIPS architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Compute Acceleration Framework; - ACPI drivers; - Drivers core; - Ublk userspace block driver; - Virtio block driver; - Bluetooth drivers; - Buffer Sharing and Synchronization framework; - DMA engine subsystem; - EFI core; - GPIO subsystem; - GPU drivers; - HID subsystem; - Microsoft Hyper-V drivers; - Hardware monitoring drivers; - I3C subsystem; - IIO ADC drivers; - IIO subsystem; - InfiniBand drivers; - IOMMU subsystem; - LED subsystem; - Multiple devices driver; - Media drivers; - Microchip PCI driver; - MTD block device drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - NVME drivers; - PCI subsystem; - PHY drivers; - Pin controllers subsystem; - x86 platform drivers; - i.MX PM domains; - Power supply drivers; - Voltage and Current Regulator drivers; - SCSI subsystem; - i.MX SoC drivers; - SPI subsystem; - UFS subsystem; - USB Gadget drivers; - TDX Guest driver; - AFS file system; - BTRFS file system; - Ceph distributed file system; - File systems infrastructure; - F2FS file system; - JFFS…