Hello, syzbot found the following crash on: HEAD commit: cee5a428 Add linux-next specific files for 20200203 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=167acbf1e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=ea1325a05ecd7b98 dashboard link: https://syzkaller.appspot.com/bug?extid=c3c5bdea7863886115dc compiler: gcc (GCC) 9.0.0 20181231 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+c3c5bdea7863886115dc@xxxxxxxxxxxxxxxxxxxxxxxxx can: request_module (can-proto-0) failed. can: request_module (can-proto-0) failed. can: request_module (can-proto-0) failed. ================================================================== BUG: KASAN: use-after-free in l2cap_sock_release+0x24c/0x290 net/bluetooth/l2cap_sock.c:1212 Read of size 8 at addr ffff8880944904a0 by task syz-fuzzer/9751 CPU: 0 PID: 9751 Comm: syz-fuzzer Not tainted 5.5.0-next-20200203-syzkaller #0 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+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 l2cap_sock_release+0x24c/0x290 net/bluetooth/l2cap_sock.c:1212 __sock_release+0xce/0x280 net/socket.c:605 sock_close+0x1e/0x30 net/socket.c:1283 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:278 [inline] do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4afb40 Code: 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 49 c7 c2 00 00 00 00 49 c7 c0 00 00 00 00 49 c7 c1 00 00 00 00 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 28 ff ff ff ff 48 c7 44 24 30 RSP: 002b:000000c00020b540 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 000000c00002e500 RCX: 00000000004afb40 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000c00020b580 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000000cc R13: 00000000000000cb R14: 0000000000000200 R15: 0000000000000200 Allocated by task 9751: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x163/0x770 mm/slab.c:3665 kmalloc include/linux/slab.h:560 [inline] sk_prot_alloc+0x23a/0x310 net/core/sock.c:1603 sk_alloc+0x39/0xfd0 net/core/sock.c:1657 l2cap_sock_alloc.constprop.0+0x37/0x230 net/bluetooth/l2cap_sock.c:1603 l2cap_sock_create+0x11e/0x1c0 net/bluetooth/l2cap_sock.c:1649 bt_sock_create+0x16a/0x2d0 net/bluetooth/af_bluetooth.c:130 __sock_create+0x3ce/0x730 net/socket.c:1433 sock_create net/socket.c:1484 [inline] __sys_socket+0x103/0x220 net/socket.c:1526 __do_sys_socket net/socket.c:1535 [inline] __se_sys_socket net/socket.c:1533 [inline] __x64_sys_socket+0x73/0xb0 net/socket.c:1533 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9751: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 sk_prot_free net/core/sock.c:1640 [inline] __sk_destruct+0x5d8/0x7f0 net/core/sock.c:1724 sk_destruct+0xd5/0x110 net/core/sock.c:1739 __sk_free+0xfb/0x3f0 net/core/sock.c:1750 sk_free+0x83/0xb0 net/core/sock.c:1761 sock_put include/net/sock.h:1719 [inline] l2cap_sock_kill+0x160/0x190 net/bluetooth/l2cap_sock.c:1058 l2cap_sock_release+0x1c3/0x290 net/bluetooth/l2cap_sock.c:1210 __sock_release+0xce/0x280 net/socket.c:605 sock_close+0x1e/0x30 net/socket.c:1283 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:278 [inline] do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888094490000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 1184 bytes inside of 2048-byte region [ffff888094490000, ffff888094490800) The buggy address belongs to the page: page:ffffea0002512400 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00025123c8 ffffea00021bf608 ffff8880aa400e00 raw: 0000000000000000 ffff888094490000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888094490380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888094490400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888094490480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888094490500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888094490580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This bug is generated by a bot. 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