================================================================== BUG: KASAN: use-after-free in handle_userfault+0x1364/0x1550 fs/userfaultfd.c:407 Read of size 8 at addr ffff88807ac4ff90 by task syz-executor.2/24320 CPU: 0 PID: 24320 Comm: syz-executor.2 Not tainted 5.18.0-rc6-next-20220512-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+0xeb/0x495 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 handle_userfault+0x1364/0x1550 fs/userfaultfd.c:407 shmem_getpage_gfp+0x1ab6/0x1f30 mm/shmem.c:1859 shmem_fault+0x1ae/0x750 mm/shmem.c:2078 __do_fault+0x107/0x650 mm/memory.c:4172 do_read_fault mm/memory.c:4518 [inline] do_fault mm/memory.c:4647 [inline] handle_pte_fault mm/memory.c:4910 [inline] __handle_mm_fault+0x2757/0x40f0 mm/memory.c:5049 handle_mm_fault+0x1c8/0x790 mm/memory.c:5147 do_user_addr_fault+0x489/0x11c0 arch/x86/mm/fault.c:1397 handle_page_fault arch/x86/mm/fault.c:1484 [inline] exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1540 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:570 RIP: 0033:0x7f9983a27c93 Code: 00 00 00 00 00 66 90 48 89 7c 24 f0 48 89 74 24 e8 48 89 54 24 e0 48 89 4c 24 d8 48 8b 4c 24 f0 48 8b 74 24 e8 4c 8b 44 24 e0 <8b> 81 0c 01 00 00 44 8b 89 08 01 00 00 48 8b 54 24 d8 c1 e0 04 8d RSP: 002b:00007f9984c2e158 EFLAGS: 00010216 RAX: 00007f9983a27c70 RBX: 00007f9983b9bf60 RCX: 0000000020816000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020816000 RBP: 00007f9983ae308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000020816000 R11: 0000000000000000 R12: 0000000000000000 R13: 00007fff2a0de8df R14: 00007f9984c2e300 R15: 0000000000022000 Allocated by task 24320: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:436 [inline] __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook mm/slab.h:750 [inline] slab_alloc_node mm/slub.c:3214 [inline] slab_alloc mm/slub.c:3222 [inline] __kmem_cache_alloc_lru mm/slub.c:3229 [inline] kmem_cache_alloc+0x142/0x3b0 mm/slub.c:3239 __do_sys_userfaultfd+0x9b/0x3e0 fs/userfaultfd.c:2098 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Freed by task 24320: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1727 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1753 slab_free mm/slub.c:3507 [inline] kmem_cache_free+0xdd/0x5a0 mm/slub.c:3524 userfaultfd_ctx_put fs/userfaultfd.c:180 [inline] userfaultfd_ctx_put+0x312/0x400 fs/userfaultfd.c:168 handle_userfault+0xfb6/0x1550 fs/userfaultfd.c:555 shmem_getpage_gfp+0x1ab6/0x1f30 mm/shmem.c:1859 shmem_fault+0x1ae/0x750 mm/shmem.c:2078 __do_fault+0x107/0x650 mm/memory.c:4172 do_read_fault mm/memory.c:4518 [inline] do_fault mm/memory.c:4647 [inline] handle_pte_fault mm/memory.c:4910 [inline] __handle_mm_fault+0x2757/0x40f0 mm/memory.c:5049 handle_mm_fault+0x1c8/0x790 mm/memory.c:5147 do_user_addr_fault+0x489/0x11c0 arch/x86/mm/fault.c:1397 handle_page_fault arch/x86/mm/fault.c:1484 [inline] exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1540 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:570 The buggy address belongs to the object at ffff88807ac4fe00 which belongs to the cache userfaultfd_ctx_cache of size 408 The buggy address is located 400 bytes inside of 408-byte region [ffff88807ac4fe00, ffff88807ac4ff98) The buggy address belongs to the physical page: page:ffffea0001eb1380 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88807ac4fc00 pfn:0x7ac4e head:ffffea0001eb1380 order:1 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000122 ffff8880191433c0 raw: ffff88807ac4fc00 0000000080100005 00000001ffffffff 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 9950, tgid 9938 (syz-executor.2), ts 399291642182, free_ts 396970731545 prep_new_page mm/page_alloc.c:2431 [inline] get_page_from_freelist+0x129e/0x3dd0 mm/page_alloc.c:4176 __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5396 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280 alloc_slab_page mm/slub.c:1797 [inline] allocate_slab+0x26c/0x3c0 mm/slub.c:1942 new_slab mm/slub.c:2002 [inline] ___slab_alloc+0x985/0xd90 mm/slub.c:3002 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3089 slab_alloc_node mm/slub.c:3180 [inline] slab_alloc mm/slub.c:3222 [inline] __kmem_cache_alloc_lru mm/slub.c:3229 [inline] kmem_cache_alloc+0x360/0x3b0 mm/slub.c:3239 __do_sys_userfaultfd+0x9b/0x3e0 fs/userfaultfd.c:2098 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1346 [inline] free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1396 free_unref_page_prepare mm/page_alloc.c:3318 [inline] free_unref_page+0x19/0x6a0 mm/page_alloc.c:3413 kasan_depopulate_vmalloc_pte+0x5c/0x70 mm/kasan/shadow.c:359 apply_to_pte_range mm/memory.c:2640 [inline] apply_to_pmd_range mm/memory.c:2684 [inline] apply_to_pud_range mm/memory.c:2720 [inline] apply_to_p4d_range mm/memory.c:2756 [inline] __apply_to_page_range+0x68c/0x1030 mm/memory.c:2790 kasan_release_vmalloc+0xa7/0xc0 mm/kasan/shadow.c:469 __purge_vmap_area_lazy+0x8f9/0x1c50 mm/vmalloc.c:1722 drain_vmap_area_work+0x52/0xe0 mm/vmalloc.c:1751 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:297 Memory state around the buggy address: ffff88807ac4fe80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807ac4ff00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807ac4ff80: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88807ac50000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88807ac50080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================