KASAN: use-after-free Read in kfree_skb

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: ff33472c Linux 4.14.134
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=113b547c600000
kernel config: https://syzkaller.appspot.com/x/.config?x=3559c2b3fb5dd4b2
dashboard link: https://syzkaller.appspot.com/bug?extid=936d4a1552d3614148dd
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+936d4a...@syzkaller.appspotmail.com

Bluetooth: Invalid header checksum
==================================================================
BUG: KASAN: use-after-free in __read_once_size
/./include/linux/compiler.h:183 [inline]
BUG: KASAN: use-after-free in atomic_read
/./arch/x86/include/asm/atomic.h:27 [inline]
BUG: KASAN: use-after-free in refcount_read /./include/linux/refcount.h:42
[inline]
BUG: KASAN: use-after-free in skb_unref /./include/linux/skbuff.h:952
[inline]
BUG: KASAN: use-after-free in kfree_skb+0x2e9/0x340 /net/core/skbuff.c:659
Read of size 4 at addr ffff8880a0168b24 by task kworker/u4:6/8999

CPU: 1 PID: 8999 Comm: kworker/u4:6 Not tainted 4.14.134 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
Call Trace:
__dump_stack /lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x19c /lib/dump_stack.c:53
print_address_description.cold+0x7c/0x1dc /mm/kasan/report.c:252
kasan_report_error /mm/kasan/report.c:351 [inline]
kasan_report /mm/kasan/report.c:409 [inline]
kasan_report.cold+0xa9/0x2af /mm/kasan/report.c:393
__asan_report_load4_noabort+0x14/0x20 /mm/kasan/report.c:429
__read_once_size /./include/linux/compiler.h:183 [inline]
atomic_read /./arch/x86/include/asm/atomic.h:27 [inline]
refcount_read /./include/linux/refcount.h:42 [inline]
skb_unref /./include/linux/skbuff.h:952 [inline]
kfree_skb+0x2e9/0x340 /net/core/skbuff.c:659
h5_reset_rx+0x4c/0x100 /drivers/bluetooth/hci_h5.c:499
h5_rx_3wire_hdr+0x2af/0x370 /drivers/bluetooth/hci_h5.c:409
h5_recv+0x25c/0x3f0 /drivers/bluetooth/hci_h5.c:532
hci_uart_tty_receive+0x1f4/0x4d0 /drivers/bluetooth/hci_ldisc.c:603
tty_ldisc_receive_buf+0x14d/0x1a0 /drivers/tty/tty_buffer.c:459
tty_port_default_receive_buf+0x73/0xa0 /drivers/tty/tty_port.c:37
receive_buf /drivers/tty/tty_buffer.c:475 [inline]
flush_to_ldisc+0x1ec/0x400 /drivers/tty/tty_buffer.c:527
process_one_work+0x863/0x1600 /kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 /kernel/workqueue.c:2248
kthread+0x319/0x430 /kernel/kthread.c:232
ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:404

Allocated by task 8999:
save_stack_trace+0x16/0x20 /arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 /mm/kasan/kasan.c:447
set_track /mm/kasan/kasan.c:459 [inline]
kasan_kmalloc /mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 /mm/kasan/kasan.c:529
kasan_slab_alloc+0xf/0x20 /mm/kasan/kasan.c:489
kmem_cache_alloc_node+0x144/0x780 /mm/slab.c:3642
__alloc_skb+0x9c/0x500 /net/core/skbuff.c:193
alloc_skb /./include/linux/skbuff.h:980 [inline]
bt_skb_alloc /./include/net/bluetooth/bluetooth.h:336 [inline]
h5_rx_pkt_start+0xc2/0x260 /drivers/bluetooth/hci_h5.c:443
h5_recv+0x25c/0x3f0 /drivers/bluetooth/hci_h5.c:532
hci_uart_tty_receive+0x1f4/0x4d0 /drivers/bluetooth/hci_ldisc.c:603
tty_ldisc_receive_buf+0x14d/0x1a0 /drivers/tty/tty_buffer.c:459
tty_port_default_receive_buf+0x73/0xa0 /drivers/tty/tty_port.c:37
receive_buf /drivers/tty/tty_buffer.c:475 [inline]
flush_to_ldisc+0x1ec/0x400 /drivers/tty/tty_buffer.c:527
process_one_work+0x863/0x1600 /kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 /kernel/workqueue.c:2248
kthread+0x319/0x430 /kernel/kthread.c:232
ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:404

Freed by task 9032:
save_stack_trace+0x16/0x20 /arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 /mm/kasan/kasan.c:447
set_track /mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 /mm/kasan/kasan.c:524
__cache_free /mm/slab.c:3496 [inline]
kmem_cache_free+0x83/0x2b0 /mm/slab.c:3758
kfree_skbmem /net/core/skbuff.c:586 [inline]
kfree_skbmem+0xac/0x120 /net/core/skbuff.c:580
__kfree_skb /net/core/skbuff.c:646 [inline]
kfree_skb+0xbd/0x340 /net/core/skbuff.c:663
h5_reset_rx+0x4c/0x100 /drivers/bluetooth/hci_h5.c:499
h5_rx_3wire_hdr+0x2af/0x370 /drivers/bluetooth/hci_h5.c:409
h5_recv+0x25c/0x3f0 /drivers/bluetooth/hci_h5.c:532
hci_uart_tty_receive+0x1f4/0x4d0 /drivers/bluetooth/hci_ldisc.c:603
tiocsti /drivers/tty/tty_io.c:2186 [inline]
tty_ioctl+0xded/0x1320 /drivers/tty/tty_io.c:2572
vfs_ioctl /fs/ioctl.c:46 [inline]
file_ioctl /fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 /fs/ioctl.c:684
SYSC_ioctl /fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 /fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 /arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8880a0168a40
which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of
232-byte region [ffff8880a0168a40, ffff8880a0168b28)
The buggy address belongs to the page:
page:ffffea0002805a00 count:1 mapcount:0 mapping:ffff8880a0168040
index:0xffff8880a0168680
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff8880a0168040 ffff8880a0168680 000000010000000b
raw: ffffea000271b6e0 ffffea0002940020 ffff88821b757240 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a0168a00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff8880a0168a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8880a0168b00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880a0168b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a0168c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 64f46940 Linux 4.19.62
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=151064ec600000
kernel config: https://syzkaller.appspot.com/x/.config?x=5a320a3fedf4c460
dashboard link: https://syzkaller.appspot.com/bug?extid=b92eb4b74ca4c06dec76

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+b92eb4...@syzkaller.appspotmail.com

Bluetooth: hci0: sending frame failed (-49)
Bluetooth: hci0: command 0x1001 tx timeout
Bluetooth: hci0: sending frame failed (-49)
Bluetooth: hci0: command 0x1009 tx timeout
==================================================================
BUG: KASAN: use-after-free in atomic_read
include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43
[inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:967 [inline]
BUG: KASAN: use-after-free in kfree_skb+0x38/0x390 net/core/skbuff.c:659
Read of size 4 at addr ffff88808facbce4 by task syz-executor.0/12252

CPU: 1 PID: 12252 Comm: syz-executor.0 Not tainted 4.19.62 #36

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
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
refcount_read include/linux/refcount.h:43 [inline]
skb_unref include/linux/skbuff.h:967 [inline]
kfree_skb+0x38/0x390 net/core/skbuff.c:659
bcsp_close+0xc7/0x130 drivers/bluetooth/hci_bcsp.c:763
hci_uart_tty_close+0x1ea/0x250 drivers/bluetooth/hci_ldisc.c:542
tty_ldisc_close.isra.0+0xaf/0xe0 drivers/tty/tty_ldisc.c:486
tty_ldisc_kill+0x4b/0xc0 drivers/tty/tty_ldisc.c:632
tty_ldisc_release+0xc6/0x280 drivers/tty/tty_ldisc.c:799
tty_release_struct+0x1b/0x50 drivers/tty/tty_io.c:1611
tty_release+0xbcb/0xe90 drivers/tty/tty_io.c:1784
__fput+0x2dd/0x8b0 fs/file_table.c:278
____fput+0x16/0x20 fs/file_table.c:309
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413511
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffcd2865940 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000413511
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: 00000000f58711af R09: 0000000092eccc80
R10: 00007ffcd2865a20 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 00000000007605c0 R15: ffffffffffffffff

Allocated by task 23:
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
kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490
kmem_cache_alloc_node+0x144/0x710 mm/slab.c:3649
__alloc_skb+0xd5/0x5f0 net/core/skbuff.c:193
alloc_skb include/linux/skbuff.h:995 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
bcsp_recv+0x8c7/0x13a0 drivers/bluetooth/hci_bcsp.c:685
hci_uart_tty_receive+0x225/0x530 drivers/bluetooth/hci_ldisc.c:607
tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:460
tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
receive_buf drivers/tty/tty_buffer.c:476 [inline]
flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:528
process_one_work+0x989/0x1750 kernel/workqueue.c:2153
worker_thread+0x98/0xe40 kernel/workqueue.c:2296
kthread+0x354/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Freed by task 23:
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]
kmem_cache_free+0x86/0x260 mm/slab.c:3765
kfree_skbmem net/core/skbuff.c:586 [inline]
kfree_skbmem+0xcb/0x150 net/core/skbuff.c:580
__kfree_skb net/core/skbuff.c:646 [inline]
kfree_skb net/core/skbuff.c:663 [inline]
kfree_skb+0xf0/0x390 net/core/skbuff.c:657
bcsp_recv+0x2d8/0x13a0 drivers/bluetooth/hci_bcsp.c:623
hci_uart_tty_receive+0x225/0x530 drivers/bluetooth/hci_ldisc.c:607
tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:460
tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
receive_buf drivers/tty/tty_buffer.c:476 [inline]
flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:528
process_one_work+0x989/0x1750 kernel/workqueue.c:2153
worker_thread+0x98/0xe40 kernel/workqueue.c:2296
kthread+0x354/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff88808facbc00

which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of

232-byte region [ffff88808facbc00, ffff88808facbce8)

The buggy address belongs to the page:

page:ffffea00023eb2c0 count:1 mapcount:0 mapping:ffff8880aa18b780
index:0xffff88808facb840
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffffea0002825e48 ffffea00023c6f48 ffff8880aa18b780
raw: ffff88808facb840 ffff88808facb0c0 0000000100000005 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff88808facbb80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
ffff88808facbc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88808facbc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
^
ffff88808facbd00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff88808facbd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 10d6aa56 Linux 4.14.135
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1713ed1a600000
kernel config: https://syzkaller.appspot.com/x/.config?x=ff4089e901d1d013

dashboard link: https://syzkaller.appspot.com/bug?extid=936d4a1552d3614148dd
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12486cdc600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+936d4a...@syzkaller.appspotmail.com

Bluetooth: hci3 command 0x1009 tx timeout
Bluetooth: hci1 command 0x1009 tx timeout
Bluetooth: hci4 command 0x1009 tx timeout
Bluetooth: hci5 command 0x1009 tx timeout
==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:183
[inline]
BUG: KASAN: use-after-free in atomic_read arch/x86/include/asm/atomic.h:27
[inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:42
[inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:952 [inline]
BUG: KASAN: use-after-free in kfree_skb+0x2e9/0x340 net/core/skbuff.c:659
Read of size 4 at addr ffff8880806f08e4 by task syz-executor.4/7881

CPU: 1 PID: 7881 Comm: syz-executor.4 Not tainted 4.14.135 #31

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011

Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x19c lib/dump_stack.c:53
print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report mm/kasan/report.c:409 [inline]
kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
__read_once_size include/linux/compiler.h:183 [inline]
atomic_read arch/x86/include/asm/atomic.h:27 [inline]
refcount_read include/linux/refcount.h:42 [inline]
skb_unref include/linux/skbuff.h:952 [inline]
kfree_skb+0x2e9/0x340 net/core/skbuff.c:659
bcsp_close+0xc7/0x130 drivers/bluetooth/hci_bcsp.c:761
hci_uart_tty_close+0x1cb/0x230 drivers/bluetooth/hci_ldisc.c:538
tty_ldisc_close.isra.0+0x99/0xd0 drivers/tty/tty_ldisc.c:498
tty_ldisc_kill+0x4b/0xc0 drivers/tty/tty_ldisc.c:644
tty_ldisc_release+0xb6/0x230 drivers/tty/tty_ldisc.c:811
tty_release_struct+0x1b/0x50 drivers/tty/tty_io.c:1603
tty_release+0xaa3/0xd60 drivers/tty/tty_io.c:1776
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244
task_work_run+0x114/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x7df/0x2c10 kernel/exit.c:874
do_group_exit+0x111/0x330 kernel/exit.c:977
get_signal+0x381/0x1cd0 kernel/signal.c:2409
do_signal+0x86/0x19a0 arch/x86/kernel/signal.c:814
exit_to_usermode_loop+0x15c/0x220 arch/x86/entry/common.c:160
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457cf1
RSP: 002b:00007ffdd692cc30 EFLAGS: 00000293 ORIG_RAX: 0000000000000023
RAX: 0000000000000000 RBX: 000000000011b578 RCX: 0000000000457cf1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ffdd692cc40
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffdd692cd30 R11: 0000000000000293 R12: 000000000075bf20
R13: 000000000075c9a0 R14: 0000000000760288 R15: ffffffffffffffff

Allocated by task 6953:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3642
__alloc_skb+0x9c/0x500 net/core/skbuff.c:193
alloc_skb include/linux/skbuff.h:980 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:336 [inline]
bcsp_recv+0x38a/0x1450 drivers/bluetooth/hci_bcsp.c:684
hci_uart_tty_receive+0x1f4/0x4d0 drivers/bluetooth/hci_ldisc.c:603
tty_ldisc_receive_buf+0x14d/0x1a0 drivers/tty/tty_buffer.c:459
tty_port_default_receive_buf+0x73/0xa0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:475 [inline]
flush_to_ldisc+0x1ec/0x400 drivers/tty/tty_buffer.c:527
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 6953:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kmem_cache_free+0x83/0x2b0 mm/slab.c:3758
kfree_skbmem net/core/skbuff.c:586 [inline]
kfree_skbmem+0xac/0x120 net/core/skbuff.c:580
__kfree_skb net/core/skbuff.c:646 [inline]
kfree_skb+0xbd/0x340 net/core/skbuff.c:663
bcsp_recv+0x28c/0x1450 drivers/bluetooth/hci_bcsp.c:622
hci_uart_tty_receive+0x1f4/0x4d0 drivers/bluetooth/hci_ldisc.c:603
Bluetooth: Error in BCSP hdr checksum
tty_ldisc_receive_buf+0x14d/0x1a0 drivers/tty/tty_buffer.c:459
tty_port_default_receive_buf+0x73/0xa0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:475 [inline]
flush_to_ldisc+0x1ec/0x400 drivers/tty/tty_buffer.c:527
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff8880806f0800

which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of

232-byte region [ffff8880806f0800, ffff8880806f08e8)

The buggy address belongs to the page:

page:ffffea000201bc00 count:1 mapcount:0 mapping:ffff8880806f0080 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff8880806f0080 0000000000000000 000000010000000c
raw: ffffea000242b260 ffffea000283e3a0 ffff88821b75f240 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8880806f0780: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
ffff8880806f0800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8880806f0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
^
ffff8880806f0900: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff8880806f0980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 9a9de33a Linux 4.19.63
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10686cdc600000
kernel config: https://syzkaller.appspot.com/x/.config?x=92b8e10c68c8329

dashboard link: https://syzkaller.appspot.com/bug?extid=b92eb4b74ca4c06dec76
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=168d3d1a600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b92eb4...@syzkaller.appspotmail.com

Bluetooth: hci3: command 0x1009 tx timeout

Bluetooth: hci2: command 0x1009 tx timeout

Bluetooth: hci5: command 0x1009 tx timeout

Bluetooth: hci4: command 0x1009 tx timeout

==================================================================
BUG: KASAN: use-after-free in atomic_read
include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43
[inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:967 [inline]
BUG: KASAN: use-after-free in kfree_skb+0x38/0x390 net/core/skbuff.c:659

Read of size 4 at addr ffff88809f600164 by task syz-executor.5/8600

CPU: 0 PID: 8600 Comm: syz-executor.5 Not tainted 4.19.63 #37

exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x994/0x2fa0 kernel/exit.c:876
do_group_exit+0x135/0x370 kernel/exit.c:979
get_signal+0x3ec/0x1fc0 kernel/signal.c:2574
do_signal+0x95/0x1960 arch/x86/kernel/signal.c:821
exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:163

prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

RIP: 0033:0x459829
Code: 48 8b 6c 24 20 48 83 c4 28 c3 31 c0 eb ee 48 89 14 24 48 89 7c 24 08
48 89 4c 24 10 e8 10 a8 ff ff 0f b6 4c 24 18 48 8b 44 24 <30> 48 8b 5c 24
38 eb bb e8 1a 8a ff ff e9 75 ff ff ff cc cc cc cc
RSP: 002b:00007f17dd9cbcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075bfd0 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bfd0
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bfd4
R13: 00007ffc8712e30f R14: 00007f17dd9cc9c0 R15: 000000000075bfd4

Allocated by task 7960:

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
kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490
kmem_cache_alloc_node+0x144/0x710 mm/slab.c:3649
__alloc_skb+0xd5/0x5f0 net/core/skbuff.c:193
alloc_skb include/linux/skbuff.h:995 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
bcsp_recv+0x8c7/0x13a0 drivers/bluetooth/hci_bcsp.c:685
hci_uart_tty_receive+0x225/0x530 drivers/bluetooth/hci_ldisc.c:607
tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:460
tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
receive_buf drivers/tty/tty_buffer.c:476 [inline]
flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:528
process_one_work+0x989/0x1750 kernel/workqueue.c:2153
worker_thread+0x98/0xe40 kernel/workqueue.c:2296
kthread+0x354/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Freed by task 7960:

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]
kmem_cache_free+0x86/0x260 mm/slab.c:3765
kfree_skbmem net/core/skbuff.c:586 [inline]
kfree_skbmem+0xcb/0x150 net/core/skbuff.c:580
__kfree_skb net/core/skbuff.c:646 [inline]
kfree_skb net/core/skbuff.c:663 [inline]
kfree_skb+0xf0/0x390 net/core/skbuff.c:657
bcsp_recv+0x2d8/0x13a0 drivers/bluetooth/hci_bcsp.c:623
hci_uart_tty_receive+0x225/0x530 drivers/bluetooth/hci_ldisc.c:607
tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:460
tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
receive_buf drivers/tty/tty_buffer.c:476 [inline]
flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:528
process_one_work+0x989/0x1750 kernel/workqueue.c:2153
worker_thread+0x98/0xe40 kernel/workqueue.c:2296
kthread+0x354/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff88809f600080

which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of

232-byte region [ffff88809f600080, ffff88809f600168)

The buggy address belongs to the page:

page:ffffea00027d8000 count:1 mapcount:0 mapping:ffff8880aa346dc0 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffffea0001fdb4c8 ffffea0002030248 ffff8880aa346dc0
raw: 0000000000000000 ffff88809f600080 000000010000000c 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff88809f600000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88809f600080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88809f600100: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
^
ffff88809f600180: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff88809f600200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 10d6aa56 Linux 4.14.135
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12849954600000
kernel config: https://syzkaller.appspot.com/x/.config?x=ff4089e901d1d013

dashboard link: https://syzkaller.appspot.com/bug?extid=936d4a1552d3614148dd
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15582a30600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15c2ddb2600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+936d4a...@syzkaller.appspotmail.com

Bluetooth: hci0 sending frame failed (-49)
Bluetooth: hci0 command 0x1001 tx timeout
Bluetooth: hci0 sending frame failed (-49)
Bluetooth: hci0 command 0x1009 tx timeout

==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:183
[inline]
BUG: KASAN: use-after-free in atomic_read arch/x86/include/asm/atomic.h:27
[inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:42
[inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:952 [inline]
BUG: KASAN: use-after-free in kfree_skb+0x2e9/0x340 net/core/skbuff.c:659
Read of size 4 at addr ffff888081176ae4 by task syz-executor870/6843

CPU: 1 PID: 6843 Comm: syz-executor870 Not tainted 4.14.135 #31

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011

Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x19c lib/dump_stack.c:53
print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report mm/kasan/report.c:409 [inline]
kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
__read_once_size include/linux/compiler.h:183 [inline]
atomic_read arch/x86/include/asm/atomic.h:27 [inline]
refcount_read include/linux/refcount.h:42 [inline]
skb_unref include/linux/skbuff.h:952 [inline]
kfree_skb+0x2e9/0x340 net/core/skbuff.c:659
bcsp_close+0xc7/0x130 drivers/bluetooth/hci_bcsp.c:761
hci_uart_tty_close+0x1cb/0x230 drivers/bluetooth/hci_ldisc.c:538
tty_ldisc_close.isra.0+0x99/0xd0 drivers/tty/tty_ldisc.c:498
tty_ldisc_kill+0x4b/0xc0 drivers/tty/tty_ldisc.c:644
tty_ldisc_release+0xb6/0x230 drivers/tty/tty_ldisc.c:811
tty_release_struct+0x1b/0x50 drivers/tty/tty_io.c:1603
tty_release+0xaa3/0xd60 drivers/tty/tty_io.c:1776
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244

task_work_run+0x114/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]

do_exit+0x7df/0x2c10 kernel/exit.c:874
do_group_exit+0x111/0x330 kernel/exit.c:977

SYSC_exit_group kernel/exit.c:988 [inline]
SyS_exit_group+0x1d/0x20 kernel/exit.c:986
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43ede8
RSP: 002b:00007fff84d1de18 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ede8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004be5e8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 22:

save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3642
__alloc_skb+0x9c/0x500 net/core/skbuff.c:193
alloc_skb include/linux/skbuff.h:980 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:336 [inline]
bcsp_recv+0x38a/0x1450 drivers/bluetooth/hci_bcsp.c:684
hci_uart_tty_receive+0x1f4/0x4d0 drivers/bluetooth/hci_ldisc.c:603
tty_ldisc_receive_buf+0x14d/0x1a0 drivers/tty/tty_buffer.c:459
tty_port_default_receive_buf+0x73/0xa0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:475 [inline]
flush_to_ldisc+0x1ec/0x400 drivers/tty/tty_buffer.c:527
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 22:

save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kmem_cache_free+0x83/0x2b0 mm/slab.c:3758
kfree_skbmem net/core/skbuff.c:586 [inline]

kfree_skbmem+0xac/0x120 net/core/skbuff.c:580
__kfree_skb net/core/skbuff.c:646 [inline]

kfree_skb+0xbd/0x340 net/core/skbuff.c:663
bcsp_recv+0x28c/0x1450 drivers/bluetooth/hci_bcsp.c:622
hci_uart_tty_receive+0x1f4/0x4d0 drivers/bluetooth/hci_ldisc.c:603

tty_ldisc_receive_buf+0x14d/0x1a0 drivers/tty/tty_buffer.c:459
tty_port_default_receive_buf+0x73/0xa0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:475 [inline]
flush_to_ldisc+0x1ec/0x400 drivers/tty/tty_buffer.c:527
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff888081176a00

which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of

232-byte region [ffff888081176a00, ffff888081176ae8)

The buggy address belongs to the page:

page:ffffea0002045d80 count:1 mapcount:0 mapping:ffff888081176000 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff888081176000 0000000000000000 000000010000000c
raw: ffffea0002a246e0 ffffea0002033de0 ffff88821b75f240 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff888081176980: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
ffff888081176a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888081176a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
^
ffff888081176b00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff888081176b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 9a9de33a Linux 4.19.63
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12f8493a600000
kernel config: https://syzkaller.appspot.com/x/.config?x=92b8e10c68c8329

dashboard link: https://syzkaller.appspot.com/bug?extid=b92eb4b74ca4c06dec76
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15b243ec600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143a7426600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b92eb4...@syzkaller.appspotmail.com

IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21

==================================================================
BUG: KASAN: use-after-free in atomic_read
include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43
[inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:967 [inline]
BUG: KASAN: use-after-free in kfree_skb+0x38/0x390 net/core/skbuff.c:659

Read of size 4 at addr ffff888096e284a4 by task syz-executor237/7890

CPU: 0 PID: 7890 Comm: syz-executor237 Not tainted 4.19.63 #37

RIP: 0033:0x401330
Code: 01 f0 ff ff 0f 83 a0 0e 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f
44 00 00 83 3d 9d 23 2d 00 00 75 14 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff
ff 0f 83 74 0e 00 00 c3 48 83 ec 08 e8 da 03 00 00
RSP: 002b:00007ffcb9213b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000401330
RDX: 0000000000441819 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 000000000014577e R08: 0000000000000004 R09: 0000000000000004
R10: 0000000000000004 R11: 0000000000000246 R12: 00000000004a29b0
R13: 00000000004026c0 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the object at ffff888096e283c0

which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of

232-byte region [ffff888096e283c0, ffff888096e284a8)

The buggy address belongs to the page:

page:ffffea00025b8a00 count:1 mapcount:0 mapping:ffff88821bab2840 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffffea0001e5fd48 ffffea00026f2608 ffff88821bab2840
raw: 0000000000000000 ffff888096e28000 000000010000000c 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff888096e28380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff888096e28400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888096e28480: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
^
ffff888096e28500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888096e28580: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
==================================================================

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 03bf4876a5935ab48e4dbf56ebdffd25e44378a5
Author: Tomas Bortoli <tomasb...@gmail.com>
Date: Fri Nov 1 20:42:44 2019 +0000

Bluetooth: Fix invalid-free in bcsp_close()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1532ba49e00000
start commit: dafd6344 Linux 4.19.79
git tree: linux-4.19.y
kernel config: https://syzkaller.appspot.com/x/.config?x=f825f73d8fea6b52
dashboard link: https://syzkaller.appspot.com/bug?extid=b92eb4b74ca4c06dec76
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=162d1acf600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=171642bb600000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: Bluetooth: Fix invalid-free in bcsp_close()

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 79d404a2aa86efe4f1ade51e054318bd811cce71

Author: Tomas Bortoli <tomasb...@gmail.com>
Date: Fri Nov 1 20:42:44 2019 +0000

Bluetooth: Fix invalid-free in bcsp_close()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10b13059e00000
start commit: b98aebd2 Linux 4.14.150
git tree: linux-4.14.y
kernel config: https://syzkaller.appspot.com/x/.config?x=c52c93b368dac5a7
dashboard link: https://syzkaller.appspot.com/bug?extid=936d4a1552d3614148dd
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10e84dc8e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1577ca37600000