RSP: 002b:00007f8ec8cde028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9 RAX: ffffffffffffffda RBX: 00007f8ecad05fa0 RCX: 00007f8ecaa8ce59 RDX: 0000000000000003 RSI: 0000000000000001 RDI: 0000000000000005 RBP: 00007f8ec8cde090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000200000000400 R11: 0000000000000246 R12: 0000000000000001 R13: 00007f8ecad06038 R14: 00007f8ecad05fa0 R15: 00007ffe7936b7b8 ================================================================== BUG: KASAN: slab-use-after-free in clear_tfile_check_list+0x114/0x380 fs/eventpoll.c:2443 Read of size 8 at addr ffff8880315f6fe8 by task syz.2.1089/8951 CPU: 0 UID: 0 PID: 8951 Comm: syz.2.1089 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 clear_tfile_check_list+0x114/0x380 fs/eventpoll.c:2443 do_epoll_ctl_file+0x8fd/0xed0 fs/eventpoll.c:-1 do_epoll_ctl fs/eventpoll.c:2698 [inline] __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline] __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8ecaa8ce59 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:00007f8ec8cde028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9 RAX: ffffffffffffffda RBX: 00007f8ecad05fa0 RCX: 00007f8ecaa8ce59 RDX: 0000000000000003 RSI: 0000000000000001 RDI: 0000000000000005 RBP: 00007f8ec8cde090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000200000000400 R11: 0000000000000246 R12: 0000000000000001 R13: 00007f8ecad06038 R14: 00007f8ecad05fa0 R15: 00007ffe7936b7b8 Allocated by task 8951: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4583 [inline] slab_alloc_node mm/slub.c:4912 [inline] kmem_cache_alloc_noprof+0x33b/0x680 mm/slub.c:4919 ep_attach_file fs/eventpoll.c:1751 [inline] ep_register_epitem fs/eventpoll.c:1833 [inline] ep_insert+0x512/0x1820 fs/eventpoll.c:1876 do_epoll_ctl_file+0x8bb/0xed0 fs/eventpoll.c:2651 do_epoll_ctl fs/eventpoll.c:2698 [inline] __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline] __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 8951: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2700 [inline] slab_free mm/slub.c:6284 [inline] kmem_cache_free+0x187/0x6c0 mm/slub.c:6411 ep_remove+0x155/0x2a0 fs/eventpoll.c:1135 ep_insert+0x1372/0x1820 fs/eventpoll.c:-1 do_epoll_ctl_file+0x8bb/0xed0 fs/eventpoll.c:2651 do_epoll_ctl fs/eventpoll.c:2698 [inline] __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline] __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8880315f6fe0 which belongs to the cache ep_head of size 16 The buggy address is located 8 bytes inside of freed 16-byte region [ffff8880315f6fe0, ffff8880315f6ff0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880315f6740 pfn:0x315f6 memcg:ffff88806a4bc001 flags: 0x80000000000200(workingset|node=0|zone=1) page_type: f5(slab) raw: 0080000000000200 ffff888140ae8dc0 ffffea0000440e90 ffffea0000e1ed90 raw: ffff8880315f6740 0000000800800016 00000000f5000000 ffff88806a4bc001 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4984, tgid 4984 (udevd), ts 38753924533, free_ts 38746774538 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859 prep_new_page mm/page_alloc.c:1867 [inline] get_page_from_freelist+0x265c/0x26e0 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5300 alloc_slab_page mm/slub.c:3289 [inline] allocate_slab+0x74/0x5e0 mm/slub.c:3404 new_slab mm/slub.c:3447 [inline] refill_objects+0x33c/0x3d0 mm/slub.c:7216 refill_sheaf mm/slub.c:2827 [inline] __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4665 alloc_from_pcs mm/slub.c:4763 [inline] slab_alloc_node mm/slub.c:4897 [inline] kmem_cache_alloc_noprof+0x433/0x680 mm/slub.c:4919 ep_attach_file fs/eventpoll.c:1751 [inline] ep_register_epitem fs/eventpoll.c:1833 [inline] ep_insert+0x512/0x1820 fs/eventpoll.c:1876 do_epoll_ctl_file+0x8bb/0xed0 fs/eventpoll.c:2651 do_epoll_ctl fs/eventpoll.c:2698 [inline] __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline] __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 4989 tgid 4989 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0x10af/0x1190 mm/page_alloc.c:2950 __slab_free+0x252/0x2a0 mm/slub.c:5646 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4583 [inline] slab_alloc_node mm/slub.c:4912 [inline] __kmalloc_cache_noprof+0x338/0x690 mm/slub.c:5420 _kmalloc_noprof include/linux/slab.h:967 [inline] _kzalloc_noprof include/linux/slab.h:1284 [inline] kernfs_fop_open+0x39a/0xcb0 fs/kernfs/file.c:641 do_dentry_open+0x83d/0x13e0 fs/open.c:947 vfs_open+0x3b/0x350 fs/open.c:1052 do_open fs/namei.c:4688 [inline] path_openat+0x2eea/0x3960 fs/namei.c:4847 do_file_open+0x23e/0x4a0 fs/namei.c:4876 do_sys_openat2+0x115/0x200 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff8880315f6e80: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc ffff8880315f6f00: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc >ffff8880315f6f80: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc ^ ffff8880315f7000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880315f7080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================