================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline] BUG: KASAN: slab-use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: slab-use-after-free in membarrier_switch_mm kernel/sched/sched.h:3721 [inline] BUG: KASAN: slab-use-after-free in context_switch kernel/sched/core.c:5265 [inline] BUG: KASAN: slab-use-after-free in __schedule+0xc8d/0x6000 kernel/sched/core.c:6907 Read of size 4 at addr ffff888031ee1940 by task syz.3.16/6034 CPU: 0 UID: 0 PID: 6034 Comm: syz.3.16 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:186 [inline] kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200 instrument_atomic_read include/linux/instrumented.h:68 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] membarrier_switch_mm kernel/sched/sched.h:3721 [inline] context_switch kernel/sched/core.c:5265 [inline] __schedule+0xc8d/0x6000 kernel/sched/core.c:6907 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7091 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 class_preempt_destructor include/linux/preempt.h:468 [inline] raw_spin_unlock_irqrestore_wake include/linux/sched/wake_q.h:96 [inline] __mutex_unlock_slowpath+0x57e/0x790 kernel/locking/mutex.c:981 __rtnl_unlock+0x68/0xf0 net/core/rtnetlink.c:143 netdev_run_todo+0x2d2/0x12c0 net/core/dev.c:11673 ip_tunnel_init_net+0x4eb/0x780 net/ipv4/ip_tunnel.c:1157 vti_init_net+0x2e/0x140 net/ipv4/ip_vti.c:517 ops_init+0x1e2/0x5f0 net/core/net_namespace.c:137 setup_net+0x118/0x3a0 net/core/net_namespace.c:446 copy_net_ns+0x46f/0x7c0 net/core/net_namespace.c:581 create_new_namespaces+0x3ea/0xac0 kernel/nsproxy.c:130 unshare_nsproxy_namespaces+0xc3/0x1f0 kernel/nsproxy.c:226 ksys_unshare+0x455/0xab0 kernel/fork.c:3174 __do_sys_unshare kernel/fork.c:3245 [inline] __se_sys_unshare kernel/fork.c:3243 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3243 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faffd99bf79 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007faffe916028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007faffdc15fa0 RCX: 00007faffd99bf79 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000080 RBP: 00007faffda327e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007faffdc16038 R14: 00007faffdc15fa0 R15: 00007ffecb8c6128 Allocated by task 5821: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x2ad/0x780 mm/slub.c:5270 dup_mm kernel/fork.c:1520 [inline] copy_mm kernel/fork.c:1582 [inline] copy_process+0x72ff/0x79b0 kernel/fork.c:2223 kernel_clone+0xfc/0x930 kernel/fork.c:2654 __do_sys_clone+0xd9/0x120 kernel/fork.c:2795 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6127: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2540 [inline] slab_free mm/slub.c:6674 [inline] kmem_cache_free+0x143/0x720 mm/slub.c:6789 mmdrop include/linux/sched/mm.h:55 [inline] __mmput+0x379/0x410 kernel/fork.c:1186 mmput+0x67/0x80 kernel/fork.c:1197 exit_mm kernel/exit.c:581 [inline] do_exit+0x78a/0x2a30 kernel/exit.c:959 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x86/0x4a0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] ret_from_fork+0x95b/0xd80 arch/x86/kernel/process.c:167 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff888031ee1880 which belongs to the cache mm_struct of size 2968 The buggy address is located 192 bytes inside of freed 2968-byte region [ffff888031ee1880, ffff888031ee2418) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888031ee6e40 pfn:0x31ee0 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff88806d764481 ksm flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813ff34b40 ffffea0001e4bc00 0000000000000003 raw: ffff888031ee6e40 00000000800a0007 00000000f5000000 ffff88806d764481 head: 00fff00000000040 ffff88813ff34b40 ffffea0001e4bc00 0000000000000003 head: ffff888031ee6e40 00000000800a0007 00000000f5000000 ffff88806d764481 head: 00fff00000000003 ffffea0000c7b801 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 5581, tgid 5581 (sshd), ts 73850257364, free_ts 72297316586 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1e1/0x250 mm/page_alloc.c:1884 prep_new_page mm/page_alloc.c:1892 [inline] get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3945 __alloc_frozen_pages_noprof+0x26c/0x2410 mm/page_alloc.c:5240 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486 alloc_slab_page mm/slub.c:3075 [inline] allocate_slab mm/slub.c:3248 [inline] new_slab+0x2c4/0x440 mm/slub.c:3302 ___slab_alloc+0xdb3/0x1cb0 mm/slub.c:4656 __slab_alloc.isra.0+0x63/0x110 mm/slub.c:4779 __slab_alloc_node mm/slub.c:4855 [inline] slab_alloc_node mm/slub.c:5251 [inline] kmem_cache_alloc_noprof+0x4ec/0x780 mm/slub.c:5270 dup_mm kernel/fork.c:1520 [inline] copy_mm kernel/fork.c:1582 [inline] copy_process+0x72ff/0x79b0 kernel/fork.c:2223 kernel_clone+0xfc/0x930 kernel/fork.c:2654 __do_sys_clone+0xd9/0x120 kernel/fork.c:2795 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5488 tgid 5488 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0x822/0x1130 mm/page_alloc.c:2973 discard_slab mm/slub.c:3346 [inline] __put_partials+0x127/0x160 mm/slub.c:3886 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_node_noprof+0x303/0x880 mm/slub.c:5315 __alloc_skb+0x156/0x410 net/core/skbuff.c:679 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0xe0/0x810 net/core/skbuff.c:6715 sock_alloc_send_pskb+0x801/0x980 net/core/sock.c:2995 unix_dgram_sendmsg+0x3c7/0x1820 net/unix/af_unix.c:2130 unix_seqpacket_sendmsg+0x12a/0x1d0 net/unix/af_unix.c:2531 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x566/0x610 net/socket.c:1195 do_iter_readv_writev+0x6ee/0x920 fs/read_write.c:829 vfs_writev+0x360/0xe10 fs/read_write.c:1059 do_writev+0x28a/0x340 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 Memory state around the buggy address: ffff888031ee1800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888031ee1880: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888031ee1900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888031ee1980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888031ee1a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================