================================================================== BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2037 [inline] BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2084 Read of size 4 at addr ffff888093c40358 by task syz-executor.2/18423 CPU: 1 PID: 18423 Comm: syz-executor.2 Not tainted 5.14.0-rc6-next-20210820-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 ctx_flush_and_put fs/io_uring.c:2037 [inline] tctx_task_work+0x307/0x310 fs/io_uring.c:2084 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline] do_exit+0xbae/0x2a30 kernel/exit.c:825 do_group_exit+0x129/0x310 kernel/exit.c:922 get_signal+0x482/0x2170 kernel/signal.c:2846 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665e9 Code: Unable to access opcode bytes at RIP 0x4665bf. RSP: 002b:00007f77794d0218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 000000000056bf88 RCX: 00000000004665e9 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 000000000056bf8c RBP: 000000000056bf80 R08: 0000000000000009 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 000000000056bf8c R13: 00007ffe6b6de29f R14: 00007f77794d0300 R15: 0000000000022000 Allocated by task 18423: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0xa8/0xe0 mm/kasan/common.c:522 kmalloc include/linux/slab.h:594 [inline] kzalloc include/linux/slab.h:731 [inline] io_ring_ctx_alloc fs/io_uring.c:1237 [inline] io_uring_create fs/io_uring.c:9876 [inline] io_uring_setup+0x27d/0x2d00 fs/io_uring.c:9982 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 10152: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0x103/0x140 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1681 [inline] slab_free_freelist_hook+0x85/0x190 mm/slub.c:1706 slab_free mm/slub.c:3459 [inline] kfree+0xea/0x540 mm/slub.c:4519 io_ring_ctx_free fs/io_uring.c:8902 [inline] io_ring_exit_work+0x13c7/0x1940 fs/io_uring.c:9051 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297 worker_thread+0x65b/0x1200 kernel/workqueue.c:2444 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Last potentially related work creation: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_record_aux_stack+0xed/0x120 mm/kasan/generic.c:348 insert_work+0x48/0x370 kernel/workqueue.c:1353 __queue_work+0x5d1/0xf30 kernel/workqueue.c:1519 queue_work_on+0xf6/0x110 kernel/workqueue.c:1546 queue_work include/linux/workqueue.h:502 [inline] io_ring_ctx_wait_and_kill+0x314/0x3d0 fs/io_uring.c:9104 io_uring_release+0x3e/0x50 fs/io_uring.c:9112 __fput+0x288/0x9f0 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline] do_exit+0xbae/0x2a30 kernel/exit.c:825 do_group_exit+0x129/0x310 kernel/exit.c:922 get_signal+0x482/0x2170 kernel/signal.c:2846 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff888093c40000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 856 bytes inside of 4096-byte region [ffff888093c40000, ffff888093c41000) The buggy address belongs to the page: page:ffffea00024f1000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x93c40 head:ffffea00024f1000 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c42140 raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 8807, ts 307481674189, free_ts 307327857417 prep_new_page mm/page_alloc.c:2424 [inline] get_page_from_freelist+0xa76/0x2f90 mm/page_alloc.c:4151 __alloc_pages+0x1ba/0x510 mm/page_alloc.c:5373 alloc_pages+0x1a7/0x300 mm/mempolicy.c:2188 alloc_slab_page mm/slub.c:1744 [inline] allocate_slab mm/slub.c:1881 [inline] new_slab+0x321/0x490 mm/slub.c:1944 ___slab_alloc+0x937/0x1000 mm/slub.c:2970 __slab_alloc.constprop.0+0x51/0xa0 mm/slub.c:3057 slab_alloc_node mm/slub.c:3148 [inline] slab_alloc mm/slub.c:3190 [inline] __kmalloc+0x305/0x320 mm/slub.c:4363 kmalloc include/linux/slab.h:599 [inline] tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_check_open_permission+0x27a/0x380 security/tomoyo/file.c:771 tomoyo_file_open security/tomoyo/tomoyo.c:311 [inline] tomoyo_file_open+0xa3/0xd0 security/tomoyo/tomoyo.c:306 security_file_open+0x49/0xb0 security/security.c:1634 do_dentry_open+0x353/0x11d0 fs/open.c:813 do_open fs/namei.c:3428 [inline] path_openat+0x1cbe/0x28b0 fs/namei.c:3561 do_filp_open+0x1aa/0x400 fs/namei.c:3588 do_sys_openat2+0x16d/0x4e0 fs/open.c:1204 do_sys_open fs/open.c:1220 [inline] __do_sys_creat fs/open.c:1294 [inline] __se_sys_creat fs/open.c:1288 [inline] __x64_sys_creat+0xc9/0x120 fs/open.c:1288 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1338 [inline] free_pcp_prepare+0x377/0x860 mm/page_alloc.c:1389 free_unref_page_prepare mm/page_alloc.c:3315 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3394 qlink_free mm/kasan/quarantine.c:146 [inline] qlist_free_all+0x5a/0xd0 mm/kasan/quarantine.c:165 kasan_quarantine_reduce+0x185/0x210 mm/kasan/quarantine.c:272 __kasan_slab_alloc+0xa1/0xc0 mm/kasan/common.c:444 kasan_slab_alloc include/linux/kasan.h:254 [inline] slab_post_alloc_hook mm/slab.h:519 [inline] slab_alloc_node mm/slub.c:3182 [inline] kmem_cache_alloc_node+0x25b/0x3e0 mm/slub.c:3218 __alloc_skb+0x20b/0x340 net/core/skbuff.c:414 alloc_skb include/linux/skbuff.h:1116 [inline] alloc_skb_with_frags+0x93/0x620 net/core/skbuff.c:6073 sock_alloc_send_pskb+0x78c/0x910 net/core/sock.c:2475 mld_newpack+0x1df/0x770 net/ipv6/mcast.c:1756 add_grhead+0x25c/0x340 net/ipv6/mcast.c:1859 add_grec+0xfc6/0x1450 net/ipv6/mcast.c:1997 mld_send_initial_cr.part.0+0xfa/0x230 net/ipv6/mcast.c:2244 mld_send_initial_cr net/ipv6/mcast.c:1232 [inline] mld_dad_work+0x1d7/0x680 net/ipv6/mcast.c:2270 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297 worker_thread+0x65b/0x1200 kernel/workqueue.c:2444 Memory state around the buggy address: ffff888093c40200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093c40280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888093c40300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888093c40380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093c40400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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