================================================================== BUG: KASAN: use-after-free in relay_switch_subbuf+0x8c0/0x930 kernel/relay.c:755 Read of size 8 at addr ffff88805114acf8 by task loop4/17029 CPU: 0 PID: 17029 Comm: loop4 Not tainted 4.19.37 #5 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: syz-executor.5 invoked oom-killer: gfp_mask=0x6000c0(GFP_KERNEL), nodemask=(null), order=0, oom_score_adj=1000 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 relay_switch_subbuf+0x8c0/0x930 kernel/relay.c:755 relay_reserve include/linux/relay.h:261 [inline] trace_note.isra.0+0x5b8/0x6e0 kernel/trace/blktrace.c:93 trace_note_tsk kernel/trace/blktrace.c:124 [inline] __blk_add_trace+0xb70/0xe10 kernel/trace/blktrace.c:264 syz-executor.5 cpuset= blk_add_trace_rq+0x192/0x210 kernel/trace/blktrace.c:818 blk_add_trace_rq_complete+0x153/0x1b0 kernel/trace/blktrace.c:847 trace_block_rq_complete include/trace/events/block.h:116 [inline] blk_update_request+0x79f/0xb30 block/blk-core.c:3080 blk_mq_end_request+0x5b/0x360 block/blk-mq.c:544 syz5 lo_complete_rq+0x219/0x2f0 drivers/block/loop.c:484 __blk_mq_complete_request block/blk-mq.c:583 [inline] blk_mq_complete_request+0x3c2/0x680 block/blk-mq.c:620 loop_handle_cmd drivers/block/loop.c:1896 [inline] loop_queue_work+0x2ab/0x2388 drivers/block/loop.c:1905 mems_allowed=0-1 kthread_worker_fn+0x2c9/0x7a0 kernel/kthread.c:662 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:890 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 CPU: 1 PID: 17026 Comm: syz-executor.5 Not tainted 4.19.37 #5 Allocated by task 15591: Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 save_stack+0x45/0xd0 mm/kasan/kasan.c:448 Call Trace: set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490 dump_header+0x15e/0x929 mm/oom_kill.c:441 kmem_cache_alloc+0x12e/0x700 mm/slab.c:3559 __d_alloc+0x2e/0x9d0 fs/dcache.c:1610 d_alloc_pseudo+0x1e/0x30 fs/dcache.c:1738 alloc_file_pseudo+0xe2/0x280 fs/file_table.c:224 oom_kill_process.cold+0x10/0x6f5 mm/oom_kill.c:954 sock_alloc_file+0x4d/0x170 net/socket.c:394 sock_map_fd net/socket.c:417 [inline] __sys_socket+0x150/0x220 net/socket.c:1350 out_of_memory mm/oom_kill.c:1129 [inline] out_of_memory+0x936/0x12d0 mm/oom_kill.c:1062 __do_sys_socket net/socket.c:1355 [inline] __se_sys_socket net/socket.c:1353 [inline] __x64_sys_socket+0x73/0xb0 net/socket.c:1353 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe mem_cgroup_out_of_memory+0x1d2/0x240 mm/memcontrol.c:1397 Freed by task 15591: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 mem_cgroup_oom mm/memcontrol.c:1723 [inline] try_charge+0x1028/0x15b0 mm/memcontrol.c:2285 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x86/0x260 mm/slab.c:3765 __d_free fs/dcache.c:257 [inline] dentry_free+0xed/0x170 fs/dcache.c:348 __dentry_kill+0x45f/0x610 fs/dcache.c:580 dentry_kill+0xd7/0x5e0 fs/dcache.c:685 dput+0x570/0x6a0 fs/dcache.c:846 mem_cgroup_try_charge+0x24d/0x5e0 mm/memcontrol.c:5953 __fput+0x429/0x8b0 fs/file_table.c:291 ____fput+0x16/0x20 fs/file_table.c:309 mem_cgroup_try_charge_delay+0x1f/0xa0 mm/memcontrol.c:5968 task_work_run+0x14a/0x1c0 kernel/task_work.c:113 do_anonymous_page mm/memory.c:3176 [inline] handle_pte_fault mm/memory.c:4033 [inline] __handle_mm_fault+0x1e55/0x3f80 mm/memory.c:4159 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88805114aca0 which belongs to the cache dentry(33:syz2) of size 288 The buggy address is located 88 bytes inside of 288-byte region [ffff88805114aca0, ffff88805114adc0) handle_mm_fault+0x43f/0xb30 mm/memory.c:4196 The buggy address belongs to the page: page:ffffea0001445280 count:1 mapcount:0 mapping:ffff8880a00364c0 index:0xffff88805114a720 faultin_page mm/gup.c:518 [inline] __get_user_pages+0x609/0x1770 mm/gup.c:718 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffff8880826fa638 ffffea00020c8148 ffff8880a00364c0 populate_vma_page_range+0x20d/0x2a0 mm/gup.c:1222 raw: ffff88805114a720 ffff88805114a040 0000000100000005 ffff8880936f85c0 __mm_populate+0x204/0x380 mm/gup.c:1270 page dumped because: kasan: bad access detected page->mem_cgroup:ffff8880936f85c0 mm_populate include/linux/mm.h:2315 [inline] vm_mmap_pgoff+0x213/0x230 mm/util.c:362 Memory state around the buggy address: ffff88805114ab80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88805114ac00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff88805114ac80: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb ksys_mmap_pgoff+0xf7/0x630 mm/mmap.c:1586 ^ ffff88805114ad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88805114ad80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================