syzbot

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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_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
BUG: KASAN: slab-use-after-free in recv_work+0x6b4/0xaa0 drivers/block/nbd.c:1022
Write of size 4 at addr ffff8880324a8a78 by task kworker/u9:9/6040

CPU: 0 UID: 0 PID: 6040 Comm: kworker/u9:9 Tainted: G     U             6.14.0-rc4-syzkaller-00212-g276f98efb64a #0
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: nbd8-recv recv_work
Call Trace:
 <TASK>
 __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:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xd9/0x110 mm/kasan/report.c:634
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
 recv_work+0x6b4/0xaa0 drivers/block/nbd.c:1022
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 7756:
 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:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 nbd_alloc_and_init_config+0x97/0x2a0 drivers/block/nbd.c:1659
 nbd_genl_connect+0x491/0x1c00 drivers/block/nbd.c:2121
 genl_family_rcv_msg_doit+0x202/0x2f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x565/0x800 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2533
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:733 [inline]
 ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2573
 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2627
 __sys_sendmsg+0x16e/0x220 net/socket.c:2659
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6040:
 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:2353 [inline]
 slab_free mm/slub.c:4609 [inline]
 kfree+0x2c4/0x4d0 mm/slub.c:4757
 nbd_config_put+0x3c1/0x750 drivers/block/nbd.c:1449
 recv_work+0x6a1/0xaa0 drivers/block/nbd.c:1021
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff8880324a8a00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 120 bytes inside of
 freed 256-byte region [ffff8880324a8a00, ffff8880324a8b00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x324a8
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
ksm flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b041b40 ffffea0000d12a80 dead000000000003
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b041b40 ffffea0000d12a80 dead000000000003
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000c92a01 ffffffffffffffff 0000000000000000
head: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 7130, tgid 7123 (syz.1.329), ts 159674182603, free_ts 159639646489
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x221/0x2470 mm/page_alloc.c:4739
 alloc_pages_mpol+0x1fc/0x540 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2423 [inline]
 allocate_slab mm/slub.c:2587 [inline]
 new_slab+0x23d/0x330 mm/slub.c:2640
 ___slab_alloc+0xc5d/0x1720 mm/slub.c:3826
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 __do_kmalloc_node mm/slub.c:4293 [inline]
 __kmalloc_node_noprof+0x2f0/0x510 mm/slub.c:4300
 __kvmalloc_node_noprof+0xad/0x1a0 mm/util.c:662
 kvmalloc_array_node_noprof include/linux/slab.h:1063 [inline]
 io_alloc_cache_init+0x33/0x170 io_uring/alloc_cache.c:25
 io_ring_ctx_alloc io_uring/io_uring.c:330 [inline]
 io_uring_create io_uring/io_uring.c:3619 [inline]
 io_uring_setup+0x615/0x2200 io_uring/io_uring.c:3793
 __do_sys_io_uring_setup io_uring/io_uring.c:3820 [inline]
 __se_sys_io_uring_setup io_uring/io_uring.c:3814 [inline]
 __x64_sys_io_uring_setup+0x98/0x140 io_uring/io_uring.c:3814
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 7112 tgid 7110 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0x6db/0xfb0 mm/page_alloc.c:2660
 mm_free_pgd kernel/fork.c:815 [inline]
 __mmdrop+0xd5/0x460 kernel/fork.c:931
 mmdrop include/linux/sched/mm.h:55 [inline]
 __mmput+0x36c/0x410 kernel/fork.c:1367
 mmput+0x62/0x70 kernel/fork.c:1378
 exit_mm kernel/exit.c:570 [inline]
 do_exit+0x9ba/0x2d70 kernel/exit.c:925
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
 get_signal+0x24ed/0x26c0 kernel/signal.c:3036
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880324a8900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880324a8980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880324a8a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff8880324a8a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880324a8b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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