================================================================== 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 ffff88802600e040 by task kworker/u9:2/5844 CPU: 0 UID: 0 PID: 5844 Comm: kworker/u9:2 Not tainted 6.16.0-syzkaller-04405-g4b290aae788e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 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:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Allocated by task 10391: 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:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 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:3805 [inline] path_mount+0x1482/0x1fd0 fs/namespace.c:4120 do_mount fs/namespace.c:4133 [inline] __do_sys_mount fs/namespace.c:4344 [inline] __se_sys_mount fs/namespace.c:4321 [inline] __x64_sys_mount+0x28d/0x310 fs/namespace.c:4321 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 10391: 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:247 [inline] __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2381 [inline] slab_free mm/slub.c:4643 [inline] kfree+0x2b4/0x4d0 mm/slub.c:4842 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:3805 [inline] path_mount+0x1482/0x1fd0 fs/namespace.c:4120 do_mount fs/namespace.c:4133 [inline] __do_sys_mount fs/namespace.c:4344 [inline] __se_sys_mount fs/namespace.c:4321 [inline] __x64_sys_mount+0x28d/0x310 fs/namespace.c:4321 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802600e000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 64 bytes inside of freed 4096-byte region [ffff88802600e000, ffff88802600f000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x26008 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 ffffea0000980201 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6382, tgid 6382 (syz-executor), ts 196767538577, free_ts 196695229097 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704 prep_new_page mm/page_alloc.c:1712 [inline] get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419 alloc_slab_page mm/slub.c:2451 [inline] allocate_slab mm/slub.c:2619 [inline] new_slab+0x23b/0x330 mm/slub.c:2673 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949 __slab_alloc_node mm/slub.c:4024 [inline] slab_alloc_node mm/slub.c:4185 [inline] __do_kmalloc_node mm/slub.c:4327 [inline] __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340 kmalloc_noprof include/linux/slab.h:909 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] ops_init+0x77/0x5f0 net/core/net_namespace.c:128 setup_net+0x1ff/0x510 net/core/net_namespace.c:442 copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:574 create_new_namespaces+0x3ea/0xa90 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:218 ksys_unshare+0x45b/0xa40 kernel/fork.c:3124 __do_sys_unshare kernel/fork.c:3195 [inline] __se_sys_unshare kernel/fork.c:3193 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3193 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 page last free pid 6147 tgid 6147 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1248 [inline] __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706 discard_slab mm/slub.c:2717 [inline] __put_partials+0x16d/0x1c0 mm/slub.c:3186 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4148 [inline] slab_alloc_node mm/slub.c:4197 [inline] __kmalloc_cache_noprof+0x1f1/0x3e0 mm/slub.c:4354 kmalloc_noprof include/linux/slab.h:905 [inline] netdev_name_node_alloc net/core/dev.c:270 [inline] netdev_name_node_head_alloc net/core/dev.c:284 [inline] register_netdevice+0x4eb/0x2270 net/core/dev.c:11026 veth_newlink+0x446/0xa00 drivers/net/veth.c:1884 rtnl_newlink_create net/core/rtnetlink.c:3823 [inline] __rtnl_newlink net/core/rtnetlink.c:3940 [inline] rtnl_newlink+0xc45/0x2000 net/core/rtnetlink.c:4055 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6944 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x58d/0x850 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] __sys_sendto+0x4a3/0x520 net/socket.c:2226 __do_sys_sendto net/socket.c:2233 [inline] __se_sys_sendto net/socket.c:2229 [inline] __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2229 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 Memory state around the buggy address: ffff88802600df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88802600df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88802600e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802600e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802600e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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