CVE-2025-21753 — btrfs: fix use-after-free when attempting to join an aborted transaction

Affected: Linux, Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

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

btrfs: fix use-after-free when attempting to join an aborted transaction

When we are trying to join the current transaction and if it's aborted, we read its 'aborted' field after unlocking fs_info->trans_lock and without holding any extra reference count on it. This means that a concurrent task that is aborting the transaction may free the transaction before we read its 'aborted' field, leading to a use-after-free.

Fix this by reading the 'aborted' field while holding fs_info->trans_lock since any freeing task must first acquire that lock and set fs_info->running_transaction to NULL before freeing the transaction.

This was reported by syzbot and Dmitry with the following stack traces from KASAN:

================================================================== BUG: KASAN: slab-use-after-free in join_transaction+0xd9b/0xda0 fs/btrfs/transaction.c:278 Read of size 4 at addr ffff888011839024 by task kworker/u4:9/1128

CPU: 0 UID: 0 PID: 1128 Comm: kworker/u4:9 Not tainted 6.13.0-rc7-syzkaller-00019-gc45323b7560e #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events_unbound btrfs_async_reclaim_data_space Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x169/0x550 mm/kasan/…

USN-7510-1 — linux, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15…

Affected: Ubuntu:20.04:LTS: linux-ibm-5.15, Ubuntu:20.04:LTS: linux-lowlatency-hwe-5.15, Ubuntu:20.04:LTS: linux-oracle-5.15, Ubuntu:22.04:LTS: linux, Ubuntu:22.04:LTS: linux-gkeop, Ubuntu:22.04:LTS: linux-ibm, Ubuntu:22.04:LTS: linux-intel-iotg, Ubuntu:22.04:LTS: linux-kvm, Ubuntu:22.04:LTS: linux-lowlatency, Ubuntu:22.04:LTS: linux-nvidia and 1 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; - PowerPC architecture; - x86 architecture; - Block layer subsystem; - Network block device driver; - Bus devices; - Character device driver; - TPM device driver; - Clock framework and drivers; - GPIO subsystem; - GPU drivers; - HID subsystem; - I2C subsystem; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - PCI subsystem; - PPS (Pulse Per Second) driver; - PTP clock framework; - RapidIO drivers; - Real Time Clock drivers; - SLIMbus drivers; - QCOM SoC drivers; - Trusted Execution Environment drivers; - TTY drivers; - USB DSL drivers; - USB Device Class drivers; - USB core drivers; - USB Gadget drivers; - USB Host Controller drivers; - Renesas USBHS Controller drivers; - ACRN Hypervisor Service Module driver; - File systems infrastructure; - BTRFS file system; - F2FS file system; - Network file system (NFS) server daemon; - NILFS2 file system; - Overlay file system; - SMB network file system; - UBI file system; - KVM subsystem; - L3 Master device support module; - Process Accounting mechanism; - Padata parallel execution mechanism; - printk logging mechanism; - Scheduler infrastructure; - Timer subsystem; - Tracing infrastructure…

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CVE-2025-21753 — btrfs: fix use-after-free when attempting to join an aborted transaction

USN-7510-1 — linux, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15…