================================================================== BUG: KASAN: use-after-free in do_shrink_slab+0xbd4/0xcb0 mm/vmscan.c:456 Read of size 8 at addr ffff8801b12cf818 by task syz-executor5/31333 CPU: 0 PID: 31333 Comm: syz-executor5 Not tainted 4.18.0+ #197 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+0x1c9/0x2b4 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 do_shrink_slab+0xbd4/0xcb0 mm/vmscan.c:456 shrink_slab_memcg mm/vmscan.c:600 [inline] shrink_slab+0x7b7/0x990 mm/vmscan.c:673 shrink_node+0x429/0x16a0 mm/vmscan.c:2734 shrink_zones mm/vmscan.c:2963 [inline] do_try_to_free_pages+0x3e7/0x1290 mm/vmscan.c:3025 try_to_free_mem_cgroup_pages+0x49d/0xc90 mm/vmscan.c:3323 memory_high_write+0x283/0x310 mm/memcontrol.c:5399 cgroup_file_write+0x31f/0x840 kernel/cgroup/cgroup.c:3447 kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316 do_loop_readv_writev fs/read_write.c:703 [inline] do_iter_write+0x491/0x5f0 fs/read_write.c:961 vfs_writev+0x1f1/0x360 fs/read_write.c:1004 do_writev+0x11a/0x310 fs/read_write.c:1039 __do_sys_writev fs/read_write.c:1112 [inline] __se_sys_writev fs/read_write.c:1109 [inline] __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457089 Code: fd b4 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fac0c834c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007fac0c8356d4 RCX: 0000000000457089 RDX: 0000000000000001 RSI: 0000000020000700 RDI: 0000000000000004 RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d77f0 R14: 00000000004c834e R15: 0000000000000000 Allocated by task 30193: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 __do_kmalloc mm/slab.c:3718 [inline] __kmalloc+0x14e/0x760 mm/slab.c:3727 kmalloc_array include/linux/slab.h:635 [inline] kcalloc include/linux/slab.h:646 [inline] iter_file_splice_write+0x25d/0x1010 fs/splice.c:693 do_splice_from fs/splice.c:852 [inline] direct_splice_actor+0x128/0x190 fs/splice.c:1019 splice_direct_to_actor+0x318/0x8f0 fs/splice.c:974 do_splice_direct+0x2d4/0x420 fs/splice.c:1062 do_sendfile+0x623/0xe20 fs/read_write.c:1440 __do_sys_sendfile64 fs/read_write.c:1495 [inline] __se_sys_sendfile64 fs/read_write.c:1487 [inline] __x64_sys_sendfile64+0x15d/0x250 fs/read_write.c:1487 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 30193: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xd9/0x260 mm/slab.c:3813 iter_file_splice_write+0x78d/0x1010 fs/splice.c:777 do_splice_from fs/splice.c:852 [inline] direct_splice_actor+0x128/0x190 fs/splice.c:1019 splice_direct_to_actor+0x318/0x8f0 fs/splice.c:974 do_splice_direct+0x2d4/0x420 fs/splice.c:1062 do_sendfile+0x623/0xe20 fs/read_write.c:1440 __do_sys_sendfile64 fs/read_write.c:1495 [inline] __se_sys_sendfile64 fs/read_write.c:1487 [inline] __x64_sys_sendfile64+0x15d/0x250 fs/read_write.c:1487 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801b12cf7c0 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 88 bytes inside of 256-byte region [ffff8801b12cf7c0, ffff8801b12cf8c0) The buggy address belongs to the page: page:ffffea0006c4b3c0 count:1 mapcount:0 mapping:ffff8801dac007c0 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0007210588 ffffea0007205948 ffff8801dac007c0 raw: 0000000000000000 ffff8801b12cf040 000000010000000c 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801b12cf700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b12cf780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >ffff8801b12cf800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801b12cf880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8801b12cf900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================