RDX: 0000000000000004 RSI: 0000000000003b8e RDI: 0000000000000006 RBP: 00007ffc444cd800 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fefc1dd5fa0 R14: 00007fefc1dd5fa0 R15: 0000000000000003 ================================================================== 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_fetch_sub_release include/linux/atomic/atomic-instrumented.h:400 [inline] BUG: KASAN: slab-use-after-free in __refcount_dec include/linux/refcount.h:455 [inline] BUG: KASAN: slab-use-after-free in refcount_dec include/linux/refcount.h:476 [inline] BUG: KASAN: slab-use-after-free in iommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376 Write of size 4 at addr ffff88805ca35804 by task syz.2.49/6154 CPU: 0 UID: 0 PID: 6154 Comm: syz.2.49 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 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_fetch_sub_release include/linux/atomic/atomic-instrumented.h:400 [inline] __refcount_dec include/linux/refcount.h:455 [inline] refcount_dec include/linux/refcount.h:476 [inline] iommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376 __fput+0x402/0xb70 fs/file_table.c:468 task_work_run+0x14d/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x41c/0x4c0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fefc1b8eba9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc444cd7a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: fffffffffffffff2 RBX: 00007fefc1dd5fa0 RCX: 00007fefc1b8eba9 RDX: 0000000000000004 RSI: 0000000000003b8e RDI: 0000000000000006 RBP: 00007ffc444cd800 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fefc1dd5fa0 R14: 00007fefc1dd5fa0 R15: 0000000000000003 Allocated by task 6154: 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 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4376 [inline] __kmalloc_noprof+0x223/0x510 mm/slub.c:4388 kmalloc_noprof include/linux/slab.h:909 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] _iommufd_object_alloc+0x23/0x1a0 drivers/iommu/iommufd/main.c:40 _iommufd_object_alloc_ucmd+0xb2/0x160 drivers/iommu/iommufd/main.c:84 iommufd_fault_alloc+0x93/0x420 drivers/iommu/iommufd/eventq.c:430 iommufd_fops_ioctl+0x34d/0x540 drivers/iommu/iommufd/main.c:508 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:584 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 6154: 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 iommufd_object_abort+0x10c/0x170 drivers/iommu/iommufd/main.c:124 iommufd_fops_ioctl+0x381/0x540 drivers/iommu/iommufd/main.c:512 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:584 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 ffff88805ca35800 which belongs to the cache kmalloc-cg-512 of size 512 The buggy address is located 4 bytes inside of freed 512-byte region [ffff88805ca35800, ffff88805ca35a00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5ca34 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff888078320f01 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b84b140 dead000000000122 0000000000000000 raw: 0000000000000000 0000000080100010 00000000f5000000 ffff888078320f01 head: 00fff00000000040 ffff88801b84b140 dead000000000122 0000000000000000 head: 0000000000000000 0000000080100010 00000000f5000000 ffff888078320f01 head: 00fff00000000002 ffffea0001728d01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5225, tgid 5225 (klogd), ts 109258917562, free_ts 109239879385 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] alloc_skb_with_frags+0xe0/0x860 net/core/skbuff.c:6665 sock_alloc_send_pskb+0x7fb/0x990 net/core/sock.c:2958 unix_dgram_sendmsg+0x3e9/0x17f0 net/unix/af_unix.c:2153 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] __sys_sendto+0x4a3/0x520 net/socket.c:2228 __do_sys_sendto net/socket.c:2235 [inline] __se_sys_sendto net/socket.c:2231 [inline] __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2231 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 5873 tgid 5873 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 stack_depot_save_flags+0x352/0x9c0 lib/stackdepot.c:727 ref_tracker_free+0x11d/0x830 lib/ref_tracker.c:308 __netns_tracker_free include/net/net_namespace.h:374 [inline] put_net_track include/net/net_namespace.h:389 [inline] __sk_destruct+0x4b2/0x9a0 net/core/sock.c:2368 sk_destruct+0xc2/0xf0 net/core/sock.c:2401 __sk_free+0xf4/0x3e0 net/core/sock.c:2412 sk_free+0x6a/0x90 net/core/sock.c:2423 deferred_put_nlk_sk+0xc9/0x110 net/netlink/af_netlink.c:716 rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0x799/0x1530 kernel/rcu/tree.c:2861 handle_softirqs+0x216/0x8e0 kernel/softirq.c:579 do_softirq kernel/softirq.c:480 [inline] do_softirq+0xb2/0xf0 kernel/softirq.c:467 __local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] update_defense_level+0x5d5/0xf70 net/netfilter/ipvs/ip_vs_ctl.c:210 defense_work_handler+0x26/0xd0 net/netfilter/ipvs/ip_vs_ctl.c:235 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 Memory state around the buggy address: ffff88805ca35700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88805ca35780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88805ca35800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88805ca35880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88805ca35900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================