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Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/259fe840897d/disk-f47d2236.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/c8fb4bab2404/vmlinux-f47d2236.xz kernel image: https://storage.googleapis.com/syzbot-assets/e3144718bd67/bzImage-f47d2236.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ae2d1f6d474e1725bdc0@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 Read of size 1 at addr ffff88804f2b02c0 by task jffs2_gcd_mtd0/12364 CPU: 1 UID: 0 PID: 12364 Comm: jffs2_gcd_mtd0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026 Call Trace: 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 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:585 kasan_check_byte include/linux/kasan.h:402 [inline] lock_acquire+0x7d/0x350 kernel/locking/lockdep.c:5916 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] jffs2_garbage_collect_thread+0x1dc/0x720 fs/jffs2/background.c:94 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 Allocated by task 12363: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:409 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:426 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x3d5/0x680 mm/slub.c:5563 _kmalloc_noprof include/linux/slab.h:991 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] jffs2_init_fs_context+0x4f/0xc0 fs/jffs2/super.c:314 alloc_fs_context+0x9a3/0xd00 fs/fs_context.c:295 do_new_mount+0x177/0xb00 fs/namespace.c:3966 do_mount fs/namespace.c:4350 [inline] __do_sys_mount fs/namespace.c:4566 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4543 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 10613: 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:264 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6509 [inline] kfree+0x1c5/0x6d0 mm/slub.c:6802 deactivate_locked_super+0xbe/0x110 fs/super.c:586 cleanup_mnt+0x204/0x2a0 fs/namespace.c:1396 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 ffff88804f2b0000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 704 bytes inside of freed 4096-byte region [ffff88804f2b0000, ffff88804f2b1000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4f2b0 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x80000000000040(head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000040 ffff88813ff44140 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 0080000000000040 ffff88813ff44140 dead000000000100 dead000000000122 head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff head: 00000007f6daf3f9 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 157, tgid 157 (kworker/u8:6), ts 576233263105 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:7418 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] __do_kmalloc_node mm/slub.c:5413 [inline] __kmalloc_node_track_caller_noprof+0x61e/0x7b0 mm/slub.c:5545 kmalloc_reserve net/core/skbuff.c:637 [inline] __alloc_skb+0x2c1/0x7a0 net/core/skbuff.c:715 alloc_skb include/linux/skbuff.h:1384 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:744 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:801 [inline] nsim_dev_trap_report_work+0x2b1/0xcb0 drivers/net/netdevsim/dev.c:847 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 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 page last free pid 5567 tgid 5567 ts 576130778544 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 __slab_free+0x250/0x2a0 mm/slub.c:5823 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:361 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] __kmalloc_cache_noprof+0x353/0x680 mm/slub.c:5559 _kmalloc_noprof include/linux/slab.h:991 [inline] poll_get_entry fs/select.c:168 [inline] __pollwait+0x27f/0x430 fs/select.c:223 poll_wait include/linux/poll.h:45 [inline] pipe_poll+0x186/0x5a0 fs/pipe.c:759 vfs_poll include/linux/poll.h:82 [inline] select_poll_one fs/select.c:480 [inline] do_select+0x1016/0x1640 fs/select.c:536 core_sys_select+0x86f/0xb40 fs/select.c:677 do_pselect fs/select.c:770 [inline] __do_sys_pselect6 fs/select.c:809 [inline] __se_sys_pselect6+0x267/0x320 fs/select.c:800 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 Memory state around the buggy address: ffff88804f2b0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804f2b0200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88804f2b0280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88804f2b0300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804f2b0380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup