================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline] BUG: KASAN: slab-use-after-free in atomic_long_inc_return include/linux/atomic/atomic-instrumented.h:3609 [inline] BUG: KASAN: slab-use-after-free in bch2_dev_get fs/bcachefs/sb-members.h:114 [inline] BUG: KASAN: slab-use-after-free in bch2_get_next_dev fs/bcachefs/sb-members.h:145 [inline] BUG: KASAN: slab-use-after-free in bch2_do_discards+0x319/0x570 fs/bcachefs/alloc_background.c:1984 Write of size 8 at addr ffff88804f31c040 by task kworker/u9:0/12104 CPU: 1 UID: 0 PID: 12104 Comm: kworker/u9:0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Workqueue: bcachefs_journal journal_write_done Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xcd/0x630 mm/kasan/report.c:482 kasan_report+0xe0/0x110 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_long_inc_return include/linux/atomic/atomic-instrumented.h:3609 [inline] bch2_dev_get fs/bcachefs/sb-members.h:114 [inline] bch2_get_next_dev fs/bcachefs/sb-members.h:145 [inline] bch2_do_discards+0x319/0x570 fs/bcachefs/alloc_background.c:1984 journal_write_done+0xee4/0x1430 fs/bcachefs/journal_io.c:1821 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Allocated by task 14912: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] __bch2_dev_alloc+0xb5/0xff0 fs/bcachefs/super.c:1487 bch2_dev_alloc+0xb8/0x190 fs/bcachefs/super.c:1558 bch2_fs_alloc+0x19ca/0x23f0 fs/bcachefs/super.c:1051 bch2_fs_open+0x838/0xc50 fs/bcachefs/super.c:2433 bch2_fs_get_tree+0xcb0/0x1b70 fs/bcachefs/fs.c:2472 vfs_get_tree+0x8e/0x340 fs/super.c:1815 do_new_mount fs/namespace.c:3808 [inline] path_mount+0x1513/0x2000 fs/namespace.c:4123 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount fs/namespace.c:4324 [inline] __x64_sys_mount+0x28d/0x310 fs/namespace.c:4324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 14912: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kfree+0x2b4/0x4d0 mm/slub.c:4894 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1e7/0x5a0 lib/kobject.c:737 bch2_fs_free+0x225/0x420 fs/bcachefs/super.c:728 bch2_fs_get_tree+0xd5e/0x1b70 fs/bcachefs/fs.c:2604 vfs_get_tree+0x8e/0x340 fs/super.c:1815 do_new_mount fs/namespace.c:3808 [inline] path_mount+0x1513/0x2000 fs/namespace.c:4123 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount fs/namespace.c:4324 [inline] __x64_sys_mount+0x28d/0x310 fs/namespace.c:4324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88804f31c000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 64 bytes inside of freed 4096-byte region [ffff88804f31c000, ffff88804f31d000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4f318 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b842140 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b842140 0000000000000000 dead000000000001 head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea00013cc601 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 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 36, tgid 36 (kworker/u8:2), ts 122672616559, free_ts 35725425743 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:2492 [inline] allocate_slab mm/slub.c:2660 [inline] new_slab+0x247/0x330 mm/slub.c:2714 ___slab_alloc+0xcf2/0x1750 mm/slub.c:3901 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3992 __slab_alloc_node mm/slub.c:4067 [inline] slab_alloc_node mm/slub.c:4228 [inline] __do_kmalloc_node mm/slub.c:4375 [inline] __kmalloc_node_track_caller_noprof+0x2ee/0x510 mm/slub.c:4395 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:600 __alloc_skb+0x166/0x380 net/core/skbuff.c:669 alloc_skb include/linux/skbuff.h:1336 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:763 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:820 [inline] nsim_dev_trap_report_work+0x2b1/0xcf0 drivers/net/netdevsim/dev.c:866 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 page last free pid 1 tgid 1 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0x7d5/0x10f0 mm/page_alloc.c:2895 __free_pages mm/page_alloc.c:5260 [inline] free_contig_range+0x183/0x4b0 mm/page_alloc.c:7091 destroy_args+0x794/0xc10 mm/debug_vm_pgtable.c:958 debug_vm_pgtable+0x1a32/0x3640 mm/debug_vm_pgtable.c:1345 do_one_initcall+0x123/0x6e0 init/main.c:1269 do_initcall_level init/main.c:1331 [inline] do_initcalls init/main.c:1347 [inline] do_basic_setup init/main.c:1366 [inline] kernel_init_freeable+0x5c2/0x910 init/main.c:1579 kernel_init+0x1c/0x2b0 init/main.c:1469 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff88804f31bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88804f31bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88804f31c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88804f31c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804f31c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================