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BUG: KASAN: use-after-free in rfcomm_dlc_get /net/bluetooth/rfcomm/core.c:360 [inline]
BUG: KASAN: use-after-free in rfcomm_dlc_exists+0x17d/0x1a0 /net/bluetooth/rfcomm/core.c:549
Read of size 1 at addr ffff8880a9055b44 by task syz-executor.0/6919

CPU: 1 PID: 6919 Comm: syz-executor.0 Not tainted 4.19.59 #32
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+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_load1_noabort+0x14/0x20 /mm/kasan/report.c:430
 rfcomm_dlc_get /net/bluetooth/rfcomm/core.c:360 [inline]
 rfcomm_dlc_exists+0x17d/0x1a0 /net/bluetooth/rfcomm/core.c:549
 __rfcomm_create_dev /net/bluetooth/rfcomm/tty.c:413 [inline]
 rfcomm_create_dev /net/bluetooth/rfcomm/tty.c:486 [inline]
 rfcomm_dev_ioctl+0x591/0x1b60 /net/bluetooth/rfcomm/tty.c:588
 rfcomm_sock_ioctl+0x90/0xb0 /net/bluetooth/rfcomm/sock.c:902
 sock_do_ioctl+0xd8/0x2f0 /net/socket.c:950
 sock_ioctl+0x325/0x610 /net/socket.c:1074
 vfs_ioctl /fs/ioctl.c:46 [inline]
 file_ioctl /fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xd5f/0x1380 /fs/ioctl.c:688
 ksys_ioctl+0xab/0xd0 /fs/ioctl.c:705
 __do_sys_ioctl /fs/ioctl.c:712 [inline]
 __se_sys_ioctl /fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x73/0xb0 /fs/ioctl.c:710
 do_syscall_64+0xfd/0x620 /arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459819
Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f0493babc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459819
RDX: 0000000020000440 RSI: 00000000400452c8 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0493bac6d4
R13: 00000000004c2def R14: 00000000004d6208 R15: 00000000ffffffff

Allocated by task 17052:
 save_stack+0x45/0xd0 /mm/kasan/kasan.c:448
 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
 kmem_cache_alloc_trace+0x152/0x760 /mm/slab.c:3625
 kmalloc /./include/linux/slab.h:515 [inline]
 kzalloc /./include/linux/slab.h:709 [inline]
 rfcomm_dlc_alloc+0x66/0x3f0 /net/bluetooth/rfcomm/core.c:305
 rfcomm_sock_alloc.constprop.0+0xb3/0x360 /net/bluetooth/rfcomm/sock.c:286
 rfcomm_sock_create+0xf3/0x2b0 /net/bluetooth/rfcomm/sock.c:329
 bt_sock_create+0x16a/0x2d0 /net/bluetooth/af_bluetooth.c:130
 __sock_create+0x3d8/0x730 /net/socket.c:1276
 sock_create /net/socket.c:1316 [inline]
 __sys_socket+0x103/0x220 /net/socket.c:1346
 __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+0xfd/0x620 /arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6710:
 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
 __cache_free /mm/slab.c:3503 [inline]
 kfree+0xcf/0x220 /mm/slab.c:3822
 rfcomm_dlc_free+0x20/0x30 /net/bluetooth/rfcomm/core.c:328
 rfcomm_dlc_put /./include/net/bluetooth/rfcomm.h:258 [inline]
 __rfcomm_create_dev /net/bluetooth/rfcomm/tty.c:417 [inline]
 rfcomm_create_dev /net/bluetooth/rfcomm/tty.c:486 [inline]
 rfcomm_dev_ioctl+0x181f/0x1b60 /net/bluetooth/rfcomm/tty.c:588
 rfcomm_sock_ioctl+0x90/0xb0 /net/bluetooth/rfcomm/sock.c:902
 sock_do_ioctl+0xd8/0x2f0 /net/socket.c:950
 sock_ioctl+0x325/0x610 /net/socket.c:1074
 vfs_ioctl /fs/ioctl.c:46 [inline]
 file_ioctl /fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xd5f/0x1380 /fs/ioctl.c:688
 ksys_ioctl+0xab/0xd0 /fs/ioctl.c:705
 __do_sys_ioctl /fs/ioctl.c:712 [inline]
 __se_sys_ioctl /fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x73/0xb0 /fs/ioctl.c:710
 do_syscall_64+0xfd/0x620 /arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a9055a00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 324 bytes inside of
 512-byte region [ffff8880a9055a00, ffff8880a9055c00)
The buggy address belongs to the page:
page:ffffea0002a41540 count:1 mapcount:0 mapping:ffff88812c3f0940 index:0xffff8880a9055780
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffffea0001d5adc8 ffffea000290d048 ffff88812c3f0940
raw: ffff8880a9055780 ffff8880a9055000 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a9055a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a9055a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a9055b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8880a9055b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a9055c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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