KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode

Status: upstream: reported on 2026/08/12 05:00
Subsystems: jffs2
Labels: prio:high actionable
[Documentation on labels]
Reported-by: syzbot+3a8099322b09d8d073d1@syzkaller.appspotmail.com
First crash: 10d, last: 1d11h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
6888de19 moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode 2026/08/12 04:07 2026/08/12 04:07 2026/08/12 05:00 f8d35649
35992835 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode 2026/08/09 04:35 2026/08/09 04:35 2026/08/09 05:19 5d63f80b
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly jffs2 report (Aug 2026) 0 (1) 2026/08/15 04:32
[syzbot] [jffs2?] KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode 0 (1) 2026/08/12 05:00

Sample crash report:
RAX: ffffffffffffffda RBX: 00007fe003705fa0 RCX: 00007fe00347e0d9
RDX: 0000000000000042 RSI: 0000200000001100 RDI: ffffffffffffff9c
RBP: 00007fe0016d6090 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000001ff R11: 0000000000000246 R12: 0000000000000002
R13: 00007fe003706038 R14: 00007fe003705fa0 R15: 00007ffd7e256058
 </TASK>
==================================================================
BUG: KASAN: slab-use-after-free in jffs2_xattr_delete_inode+0x2c8/0x2d0 fs/jffs2/xattr.c:602
Read of size 4 at addr ffff88803fd14168 by task syz.5.3773/22061

CPU: 0 UID: 0 PID: 22061 Comm: syz.5.3773 Tainted: G S                  syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [S]=CPU_OUT_OF_SPEC
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 jffs2_xattr_delete_inode+0x2c8/0x2d0 fs/jffs2/xattr.c:602
 jffs2_do_clear_inode+0x58/0x390 fs/jffs2/readinode.c:1418
 evict+0x624/0xb50 fs/inode.c:825
 jffs2_new_inode+0x49c/0xd00 fs/jffs2/fs.c:-1
 jffs2_create+0x87/0x320 fs/jffs2/dir.c:182
 lookup_open fs/namei.c:4508 [inline]
 open_last_lookups fs/namei.c:4608 [inline]
 path_openat+0x1344/0x3850 fs/namei.c:4860
 do_file_open+0x23e/0x4a0 fs/namei.c:4892
 do_sys_openat2+0x115/0x200 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1385
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe00347e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe0016d6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe003705fa0 RCX: 00007fe00347e0d9
RDX: 0000000000000042 RSI: 0000200000001100 RDI: ffffffffffffff9c
RBP: 00007fe0016d6090 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000001ff R11: 0000000000000246 R12: 0000000000000002
R13: 00007fe003706038 R14: 00007fe003705fa0 R15: 00007ffd7e256058
 </TASK>

Allocated by task 20759:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4584 [inline]
 slab_alloc_node mm/slub.c:4917 [inline]
 kmem_cache_alloc_noprof+0x355/0x650 mm/slub.c:4931
 jffs2_scan_make_ino_cache+0x89/0x1d0 fs/jffs2/scan.c:978
 jffs2_sum_process_sum_data fs/jffs2/summary.c:418 [inline]
 jffs2_sum_scan_sumnode+0x49d/0x2870 fs/jffs2/summary.c:640
 jffs2_scan_eraseblock fs/jffs2/scan.c:546 [inline]
 jffs2_scan_medium+0x807/0x70c0 fs/jffs2/scan.c:151
 jffs2_build_filesystem fs/jffs2/build.c:112 [inline]
 jffs2_do_mount_fs+0x775/0x22c0 fs/jffs2/build.c:416
 jffs2_do_fill_super+0x555/0xc50 fs/jffs2/fs.c:574
 mtd_get_sb+0x18a/0x410 drivers/mtd/mtdsuper.c:57
 mtd_get_sb_by_nr drivers/mtd/mtdsuper.c:88 [inline]
 get_tree_mtd+0x4bd/0x7d0 drivers/mtd/mtdsuper.c:158
 vfs_get_tree+0x92/0x2a0 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 10669:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kmem_cache_free+0x187/0x6c0 mm/slub.c:6504
 jffs2_free_ino_caches+0xec/0x1c0 fs/jffs2/nodelist.c:497
 jffs2_put_super+0x6c/0x170 fs/jffs2/super.c:335
 generic_shutdown_super+0x13d/0x2d0 fs/super.c:647
 kill_mtd_super+0x23/0x70 drivers/mtd/mtdsuper.c:174
 jffs2_kill_sb+0x96/0xb0 fs/jffs2/super.c:350
 deactivate_locked_super+0xbc/0x130 fs/super.c:477
 cleanup_mnt+0x3d3/0x460 fs/namespace.c:1317
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x1fa/0x750 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88803fd14140
 which belongs to the cache jffs2_inode_cache of size 48
The buggy address is located 40 bytes inside of
 freed 48-byte region [ffff88803fd14140, ffff88803fd14170)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803fd14340 pfn:0x3fd14
flags: 0x80000000000200(workingset|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000200 ffff888140427a00 ffffea000085e0d0 ffffea0000a82550
raw: ffff88803fd14340 0000000800400000 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 11991, tgid 11988 (syz.3.811), ts 660118579020, free_ts 659889977735
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x262a/0x26a0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3380
 new_slab mm/slub.c:3426 [inline]
 refill_objects+0x2d8/0x350 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x330/0x690 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 kmem_cache_alloc_noprof+0x452/0x650 mm/slub.c:4931
 jffs2_scan_make_ino_cache+0x89/0x1d0 fs/jffs2/scan.c:978
 jffs2_sum_process_sum_data fs/jffs2/summary.c:418 [inline]
 jffs2_sum_scan_sumnode+0x49d/0x2870 fs/jffs2/summary.c:640
 jffs2_scan_eraseblock fs/jffs2/scan.c:546 [inline]
 jffs2_scan_medium+0x807/0x70c0 fs/jffs2/scan.c:151
 jffs2_build_filesystem fs/jffs2/build.c:112 [inline]
 jffs2_do_mount_fs+0x775/0x22c0 fs/jffs2/build.c:416
 jffs2_do_fill_super+0x555/0xc50 fs/jffs2/fs.c:574
 mtd_get_sb+0x18a/0x410 drivers/mtd/mtdsuper.c:57
 mtd_get_sb_by_nr drivers/mtd/mtdsuper.c:88 [inline]
 get_tree_mtd+0x4bd/0x7d0 drivers/mtd/mtdsuper.c:158
 vfs_get_tree+0x92/0x2a0 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
page last free pid 20 tgid 20 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x10e7/0x11c0 mm/page_alloc.c:2950
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
 rcu_do_batch kernel/rcu/tree.c:2645 [inline]
 rcu_core kernel/rcu/tree.c:2897 [inline]
 rcu_cpu_kthread+0x950/0x1480 kernel/rcu/tree.c:2985
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88803fd14000: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
 ffff88803fd14080: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
>ffff88803fd14100: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
                                                          ^
 ffff88803fd14180: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
 ffff88803fd14200: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/17 11:27 upstream 8d3ae59288f1 905244d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/08 01:50 upstream bcc44b6785f2 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/12 00:06 upstream f5bbbfec59b4 f8d35649 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/09 10:02 linux-next 6b8c8af514d7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
* Struck through repros no longer work on HEAD.