{"cve":"CVE-2025-21753","nvd":{"published":"2025-02-27T03:15:15.950","modified":"2026-10-15T02:17:32.183","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix use-after-free when attempting to join an aborted transaction\n\nWhen we are trying to join the current transaction and if it's aborted,\nwe read its 'aborted' field after unlocking fs_info->trans_lock and\nwithout holding any extra reference count on it. This means that a\nconcurrent task that is aborting the transaction may free the transaction\nbefore we read its 'aborted' field, leading to a use-after-free.\n\nFix this by reading the 'aborted' field while holding fs_info->trans_lock\nsince any freeing task must first acquire that lock and set\nfs_info->running_transaction to NULL before freeing the transaction.\n\nThis was reported by syzbot and Dmitry with the following stack traces\nfrom KASAN:\n\n   ==================================================================\n   BUG: KASAN: slab-use-after-free in join_transaction+0xd9b/0xda0 fs/btrfs/transaction.c:278\n   Read of size 4 at addr ffff888011839024 by task kworker/u4:9/1128\n\n   CPU: 0 UID: 0 PID: 1128 Comm: kworker/u4:9 Not tainted 6.13.0-rc7-syzkaller-00019-gc45323b7560e #0\n   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\n   Workqueue: events_unbound btrfs_async_reclaim_data_space\n   Call Trace:\n    <TASK>\n    __dump_stack lib/dump_stack.c:94 [inline]\n    dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120\n    print_address_description mm/kasan/report.c:378 [inline]\n    print_report+0x169/0x550 mm/kasan/report.c:489\n    kasan_report+0x143/0x180 mm/kasan/report.c:602\n    join_transaction+0xd9b/0xda0 fs/btrfs/transaction.c:278\n    start_transaction+0xaf8/0x1670 fs/btrfs/transaction.c:697\n    flush_space+0x448/0xcf0 fs/btrfs/space-info.c:803\n    btrfs_async_reclaim_data_space+0x159/0x510 fs/btrfs/space-info.c:1321\n    process_one_work kernel/workqueue.c:3236 [inline]\n    process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317\n    worker_thread+0x870/0xd30 kernel/workqueue.c:3398\n    kthread+0x2f0/0x390 kernel/kthread.c:389\n    ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n    </TASK>\n\n   Allocated by task 5315:\n    kasan_save_stack mm/kasan/common.c:47 [inline]\n    kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n    poison_kmalloc_redzone mm/kasan/common.c:377 [inline]\n    __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394\n    kasan_kmalloc include/linux/kasan.h:260 [inline]\n    __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329\n    kmalloc_noprof include/linux/slab.h:901 [inline]\n    join_transaction+0x144/0xda0 fs/btrfs/transaction.c:308\n    start_transaction+0xaf8/0x1670 fs/btrfs/transaction.c:697\n    btrfs_create_common+0x1b2/0x2e0 fs/btrfs/inode.c:6572\n    lookup_open fs/namei.c:3649 [inline]\n    open_last_lookups fs/namei.c:3748 [inline]\n    path_openat+0x1c03/0x3590 fs/namei.c:3984\n    do_filp_open+0x27f/0x4e0 fs/namei.c:4014\n    do_sys_openat2+0x13e/0x1d0 fs/open.c:1402\n    do_sys_open fs/open.c:1417 [inline]\n    __do_sys_creat fs/open.c:1495 [inline]\n    __se_sys_creat fs/open.c:1489 [inline]\n    __x64_sys_creat+0x123/0x170 fs/open.c:1489\n    do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n    do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n    entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n   Freed by task 5336:\n    kasan_save_stack mm/kasan/common.c:47 [inline]\n    kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n    kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582\n    poison_slab_object mm/kasan/common.c:247 [inline]\n    __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264\n    kasan_slab_free include/linux/kasan.h:233 [inline]\n    slab_free_hook mm/slub.c:2353 [inline]\n    slab_free mm/slub.c:4613 [inline]\n    kfree+0x196/0x430 mm/slub.c:4761\n    cleanup_transaction fs/btrfs/transaction.c:2063 [inline]\n    btrfs_commit_transaction+0x2c97/0x3720 fs/btrfs/transaction.c:2598\n    insert_balance_item+0x1284/0x20b0 fs/btrfs/volumes.c:3757\n    btrfs_balance+0x992/\n---truncated---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/6ba4663ada6c6315af23a6669d386146634808ec","https://git.kernel.org/stable/c/7e954b6bb95d67ae4d1a20e9cfd83c182cf929bc","https://git.kernel.org/stable/c/86d71a026a7f63da905db9add845c8ee88801eca","https://git.kernel.org/stable/c/8f5cff471039caa2b088060c074c2bf2081bcb01","https://git.kernel.org/stable/c/c7a53757717e68af94a56929d57f1e6daff220ec"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2025-21753","score":0.0026,"percentile":0.17504,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}