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: 50d, last: 7h29m
▶ ▼ ✨ 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 (3)
Title Replies (including bot) Last reply
[PATCH] jffs: initialize inocache to NULL when initializing a jffs2_inode_info 6 (6) 2026/09/10 03:19
[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:
RBP: 0000200000000080 R08: 00002000000002c0 R09: 0000000000000000
R10: 0000200000000080 R11: 0000000000000246 R12: 00002000000002c0
R13: 00007f58393f5ea0 R14: 0000000000000000 R15: 0000000000000000
 </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 ffff88803f942368 by task syz.3.277/7942

CPU: 0 UID: 0 PID: 7942 Comm: syz.3.277 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
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:822
 jffs2_new_inode+0x49c/0xd40 fs/jffs2/fs.c:-1
 jffs2_mkdir+0x189/0xec0 fs/jffs2/dir.c:483
 vfs_mkdir+0x408/0x620 fs/namei.c:5410
 filename_mkdirat+0x289/0x520 fs/namei.c:5443
 __do_sys_mkdirat fs/namei.c:5464 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f583b19cfc7
Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 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:00007f58393f5e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f58393f5ee0 RCX: 00007f583b19cfc7
RDX: 00000000000001ff RSI: 00002000000002c0 RDI: 00000000ffffff9c
RBP: 0000200000000080 R08: 00002000000002c0 R09: 0000000000000000
R10: 0000200000000080 R11: 0000000000000246 R12: 00002000000002c0
R13: 00007f58393f5ea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 7707:
 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:4683 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_noprof+0x360/0x690 mm/slub.c:5010
 jffs2_scan_make_ino_cache+0x89/0x1d0 fs/jffs2/scan.c:978
 jffs2_scan_dirent_node fs/jffs2/scan.c:1099 [inline]
 jffs2_scan_eraseblock fs/jffs2/scan.c:831 [inline]
 jffs2_scan_medium+0x2b58/0x70c0 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
 get_tree_mtd+0x597/0x7d0 drivers/mtd/mtdsuper.c:141
 vfs_get_tree+0x92/0x2a0 fs/super.c:1933
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3848
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4374
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 7707:
 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:2748 [inline]
 slab_free mm/slub.c:6508 [inline]
 kmem_cache_free+0x187/0x6d0 mm/slub.c:6635
 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:755
 kill_mtd_super+0x23/0x70 drivers/mtd/mtdsuper.c:174
 jffs2_kill_sb+0x96/0xb0 fs/jffs2/super.c:350
 deactivate_locked_super+0xbc/0x110 fs/super.c:589
 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+0x204/0x770 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:343 [inline]
 do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88803f942340
 which belongs to the cache jffs2_inode_cache of size 48
The buggy address is located 40 bytes inside of
 freed 48-byte region [ffff88803f942340, ffff88803f942370)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803f9421c0 pfn:0x3f942
flags: 0x80000000000200(workingset|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000200 ffff88801e7ddb40 ffffea0000b06d10 ffff88801e7ee088
raw: ffff88803f9421c0 0000000200400007 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 5812, tgid 5811 (syz.0.1), ts 117270914272
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x2591/0x2600 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x230/0x5c0 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab+0x7d/0x620 mm/slub.c:3462
 new_slab mm/slub.c:3513 [inline]
 refill_objects+0x2d8/0x350 mm/slub.c:7417
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x339/0x690 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 kmem_cache_alloc_noprof+0x45d/0x690 mm/slub.c:5010
 jffs2_scan_make_ino_cache+0x89/0x1d0 fs/jffs2/scan.c:978
 jffs2_scan_inode_node fs/jffs2/scan.c:1025 [inline]
 jffs2_scan_eraseblock fs/jffs2/scan.c:814 [inline]
 jffs2_scan_medium+0x33bd/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
 get_tree_mtd+0x597/0x7d0 drivers/mtd/mtdsuper.c:141
 vfs_get_tree+0x92/0x2a0 fs/super.c:1933
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3848
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4374
page last free pid 20 tgid 20 ts 116574917198 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0xf8e/0x1070 mm/page_alloc.c:2962
 __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:2650 [inline]
 rcu_core kernel/rcu/tree.c:2919 [inline]
 rcu_cpu_kthread+0xb2c/0x1740 kernel/rcu/tree.c:3007
 smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
 kthread+0x38b/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:
 ffff88803f942200: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
 ffff88803f942280: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
>ffff88803f942300: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
                                                          ^
 ffff88803f942380: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
 ffff88803f942400: fa fb fb fb fb fb fc fc fa fb fb fb fb fb fc fc
==================================================================

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/15 22:38 upstream f6e7b42bf05b 2daa4bb5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/17 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
2026/09/22 06:52 upstream f0100363d8c3 e12281bd .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
2026/09/11 01:51 upstream 08df884136f1 1fe56c0a .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
2026/09/08 02:25 upstream 28924df2a08f 680aa3e1 .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
2026/08/23 14:06 upstream 818bebeb63dd 1e72964b .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
2026/08/19 05:11 upstream b126f6f5940f 1e72964b .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
2026/08/12 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
2026/09/19 10:43 upstream 50d05c7c76c9 853b104b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/09/07 21:47 upstream df2908090cda 5e4626f5 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/09/27 03:29 linux-next f5f84daefcd9 a3c7249d .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
2026/09/25 06:49 linux-next 4c253ac4b29b f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/09/13 04:32 linux-next 9d80aa4617b3 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/27 20:47 linux-next 3d83758432b5 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/25 19:48 linux-next a8406e6c0b79 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in jffs2_xattr_delete_inode
2026/08/25 07:02 linux-next 4b18edbd8e70 23caa175 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce 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.