================================================================== BUG: KASAN: use-after-free in filemap_fault+0x25f5/0x2a00 mm/filemap.c:2559 Read of size 8 at addr ffff888050a159c8 by task syz-executor4/17152 CPU: 0 PID: 17152 Comm: syz-executor4 Not tainted 4.20.0-next-20190103 #5 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1db/0x2d0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 filemap_fault+0x25f5/0x2a00 mm/filemap.c:2559 ext4_filemap_fault+0x83/0xaf fs/ext4/inode.c:6327 __do_fault+0x176/0x7b0 mm/memory.c:3013 do_shared_fault mm/memory.c:3479 [inline] do_fault mm/memory.c:3554 [inline] handle_pte_fault mm/memory.c:3781 [inline] __handle_mm_fault+0x3500/0x55a0 mm/memory.c:3905 handle_mm_fault+0x4ec/0xc80 mm/memory.c:3942 do_user_addr_fault arch/x86/mm/fault.c:1475 [inline] __do_page_fault+0x5da/0xd60 arch/x86/mm/fault.c:1541 do_page_fault+0xe6/0x7d8 arch/x86/mm/fault.c:1572 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143 RIP: 0010:copy_user_enhanced_fast_string+0xe/0x20 arch/x86/lib/copy_user_64.S:181 Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 1f 00 c3 0f 1f 80 00 00 00 00 0f 1f 00 83 fa 40 0f 82 70 ff ff ff 89 d1 a4 31 c0 0f 1f 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 83 RSP: 0018:ffff888090d87470 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000000001000 RCX: 0000000000001000 RDX: 0000000000001000 RSI: ffff888089ae2000 RDI: 0000000020116000 RBP: ffff888090d874a8 R08: ffffed101135c600 R09: 0000000000000000 R10: ffffed101135c5ff R11: ffff888089ae2fff R12: 0000000020116000 R13: ffff888089ae2000 R14: 0000000020117000 R15: 00007ffffffff000 copy_page_to_iter_iovec lib/iov_iter.c:210 [inline] copy_page_to_iter+0x433/0x1000 lib/iov_iter.c:886 generic_file_buffered_read mm/filemap.c:2183 [inline] generic_file_read_iter+0xbb1/0x2d40 mm/filemap.c:2360 ext4_file_read_iter+0x180/0x3c0 fs/ext4/file.c:77 call_read_iter include/linux/fs.h:1853 [inline] do_iter_readv_writev+0x799/0xbc0 fs/read_write.c:678 do_iter_read+0x27c/0x660 fs/read_write.c:922 vfs_readv+0x175/0x1c0 fs/read_write.c:986 do_preadv+0x1c4/0x280 fs/read_write.c:1070 __do_sys_preadv fs/read_write.c:1120 [inline] __se_sys_preadv fs/read_write.c:1115 [inline] __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1115 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457ec9 Code: 6d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f09d56bdc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457ec9 RDX: 1000000000000212 RSI: 00000000200075c0 RDI: 000000000000000b RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f09d56be6d4 R13: 00000000004c46f0 R14: 00000000004d79d8 R15: 00000000ffffffff Allocated by task 17147: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] kasan_kmalloc mm/kasan/common.c:482 [inline] kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:397 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3541 vm_area_alloc+0x7a/0x1d0 kernel/fork.c:331 mmap_region+0x93b/0x1ca0 mm/mmap.c:1756 do_mmap+0xa09/0x1220 mm/mmap.c:1559 do_mmap_pgoff include/linux/mm.h:2421 [inline] vm_mmap_pgoff+0x20b/0x2b0 mm/util.c:350 ksys_mmap_pgoff+0x4f8/0x650 mm/mmap.c:1609 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 17160: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452 __cache_free mm/slab.c:3485 [inline] kmem_cache_free+0x86/0x260 mm/slab.c:3747 vm_area_free+0x1d/0x30 kernel/fork.c:350 remove_vma+0x142/0x180 mm/mmap.c:185 remove_vma_list mm/mmap.c:2585 [inline] __do_munmap+0x72e/0xef0 mm/mmap.c:2828 do_munmap mm/mmap.c:2836 [inline] mmap_region+0x698/0x1ca0 mm/mmap.c:1729 do_mmap+0xa09/0x1220 mm/mmap.c:1559 do_mmap_pgoff include/linux/mm.h:2421 [inline] vm_mmap_pgoff+0x20b/0x2b0 mm/util.c:350 ksys_mmap_pgoff+0x4f8/0x650 mm/mmap.c:1609 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888050a15988 which belongs to the cache vm_area_struct(97:syz4) of size 200 The buggy address is located 64 bytes inside of 200-byte region [ffff888050a15988, ffff888050a15a50) The buggy address belongs to the page: page:ffffea0001428540 count:1 mapcount:0 mapping:ffff88808f0dbb40 index:0xffff888050a15250 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0002813248 ffffea0002a14208 ffff88808f0dbb40 raw: ffff888050a15250 ffff888050a15040 000000010000000e ffff88805939e3c0 page dumped because: kasan: bad access detected page->mem_cgroup:ffff88805939e3c0 Memory state around the buggy address: ffff888050a15880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888050a15900: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc >ffff888050a15980: fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888050a15a00: fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc ffff888050a15a80: fc fc fb fb fb fb fb 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