CVE-2026-74628 — net/x25: fix use-after-free of the socket by its timers

Affected: Linux

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

net/x25: fix use-after-free of the socket by its timers

The x25 timers are armed with mod_timer() and cancelled with timer_delete(), so a pending timer holds no reference on the socket and a cancel does not wait for a callback already running on another CPU.

x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall sk->sk_timer after __x25_destroy_socket() has passed its cancel point. The following __sock_put() frees the socket while the timer is still queued, and the next expiry uses freed memory. KASAN reports a slab-use-after-free on the kmalloc-2k object freed by close().

timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and x25_timer_expiry() both reach the cancels from inside the timer they would wait on, through __x25_destroy_socket() and x25_disconnect().

Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer() so that an armed timer owns a reference, and release it in both expiry handlers. Rearm the heartbeat only while sk_hashed(sk) is still true, since __x25_destroy_socket() unlinks the socket before dropping it. Arm the deferred destroy timer the same way and drop its reference in x25_destroy_timer().

Reproduced on net with KASAN, with the heartbeat period shortened so the window recurs. With this patch the reproducer no longer triggers a report and /proc/net/x25 drains.

Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

USN-8886-1 — linux-nvidia-tegra vulnerabilities

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

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: - NVDIMM (Non-Volatile Memory Device) drivers; - Handshake API; - ARM32 architecture; - ARM64 architecture; - MIPS architecture; - OpenRISC architecture; - PowerPC architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - Intel NPU Driver; - Android drivers; - Rados block device (RBD) driver; - Bluetooth drivers; - Hardware random number generator core; - TPM device driver; - CPU frequency scaling framework; - Hardware crypto device drivers; - DMA engine subsystem; - FireWire subsystem; - Arm Firmware Framework for ARMv8-A(FFA); - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - CoreSight HW tracing drivers; - I2C subsystem; - IIO ADC drivers; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - Multifunction device drivers; - Fastrpc Driver; - Amazon Nitro Secure Module driver; - MMC subsystem; - MTD block device drivers; - Ethernet bonding driver; - Network drivers; - Mellanox network drivers; - Texas Instruments network drivers; - NTB driver; - NVME drivers; - NVMEM (Non Volatile Memory) drivers; - Parport drivers…

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CVE-2026-74628 — net/x25: fix use-after-free of the socket by its timers

USN-8886-1 — linux-nvidia-tegra vulnerabilities