CVE-2024-43887 — net/tcp: Disable TCP-AO static key after RCU grace period

Affected: Linux

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

net/tcp: Disable TCP-AO static key after RCU grace period

The lifetime of TCP-AO static_key is the same as the last tcp_ao_info. On the socket destruction tcp_ao_info ceases to be with RCU grace period, while tcp-ao static branch is currently deferred destructed. The static key definition is : DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_ao_needed, HZ);

which means that if RCU grace period is delayed by more than a second and tcp_ao_needed is in the process of disablement, other CPUs may yet see tcp_ao_info which atent dead, but soon-to-be. And that breaks the assumption of static_key_fast_inc_not_disabled().

See the comment near the definition: > * The caller must make sure that the static key can't get disabled while > * in this function. It doesn't patch jump labels, only adds a user to > * an already enabled static key.

Originally it was introduced in commit eb8c507296f6 ("jump_label: Prevent key->enabled int overflow"), which is needed for the atomic contexts, one of which would be the creation of a full socket from a request socket. In that atomic context, it's known by the presence of the key (md5/ao) that the static branch is already enabled. So, the ref counter for that static branch is just incremented instead of holding the proper mutex. static_key_fast_inc_not_disabled() is just a helper for such usage case. But it must not be used if the static branch could get disabled in parallel as it's not prot…

USN-7154-1 — linux, linux-aws, linux-aws-6.8, linux-gcp, linux-gcp-6.8, linux-gke, linux-ibm, linux-lowlatency, linux-lowlatency-hwe…

Affected: Ubuntu:22.04:LTS: linux-aws-6.8, Ubuntu:22.04:LTS: linux-gcp-6.8, Ubuntu:22.04:LTS: linux-lowlatency-hwe-6.8, Ubuntu:22.04:LTS: linux-oracle-6.8, Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-aws, Ubuntu:24.04:LTS: linux-gcp, Ubuntu:24.04:LTS: linux-gke, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-lowlatency and 3 more

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; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Android drivers; - ATM drivers; - Drivers core; - Ublk userspace block driver; - Bluetooth drivers; - Character device driver; - Hardware crypto device drivers; - Buffer Sharing and Synchronization framework; - DMA engine subsystem; - Qualcomm firmware drivers; - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - I3C subsystem; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Miscellaneous) drivers; - IOMMU subsystem; - IRQ chip drivers; - LED subsystem; - Mailbox framework; - Multiple devices driver; - Media drivers; - Fastrpc Driver; - VMware VMCI Driver; - MMC subsystem; - Ethernet bonding driver; - Network drivers; - Mellanox network drivers; - Microsoft Azure Network Adapter (MANA) driver; - Near Field Communication (NFC) drivers; - NVME drivers; - Device tree and open firmware driver; - Parport drivers; - PCI subsystem; - Pin controllers subsystem; - x86 platform drivers; - Power supply drivers; - Remote Processor subsystem; - S/390…

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CVE-2024-43887 — net/tcp: Disable TCP-AO static key after RCU grace period

USN-7154-1 — linux, linux-aws, linux-aws-6.8, linux-gcp, linux-gcp-6.8, linux-gke, linux-ibm, linux-lowlatency, linux-lowlatency-hwe…