KASAN: invalid-free in skb_free_head

From: syzbot
Date: Fri Nov 01 2019 - 11:42:12 EST

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Hello,

syzbot found the following crash on:

HEAD commit: e472c64a Merge tag 'dmaengine-fix-5.4-rc6' of git://git.in..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12c36998e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=2bcb64e504d04eff
dashboard link: https://syzkaller.appspot.com/bug?extid=a0d209a4676664613e76
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b881f4e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17713f82e00000

The bug was bisected to:

commit 4ce9146e0370fcd573f0372d9b4e5a211112567c
Author: Tomas Bortoli <tomasbortoli@xxxxxxxxx>
Date: Tue May 28 13:42:58 2019 +0000

Bluetooth: hci_bcsp: Fix memory leak in rx_skb

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=133d1684e00000
final crash: https://syzkaller.appspot.com/x/report.txt?x=10bd1684e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=173d1684e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a0d209a4676664613e76@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 4ce9146e0370 ("Bluetooth: hci_bcsp: Fix memory leak in rx_skb")

==================================================================
BUG: KASAN: double-free or invalid-free in skb_free_head+0x93/0xb0 net/core/skbuff.c:591

CPU: 1 PID: 9156 Comm: syz-executor213 Not tainted 5.4.0-rc5+ #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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
kasan_report_invalid_free+0x65/0xa0 mm/kasan/report.c:468
__kasan_slab_free+0x13a/0x150 mm/kasan/common.c:450
kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
__cache_free mm/slab.c:3425 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3756
skb_free_head+0x93/0xb0 net/core/skbuff.c:591
skb_release_data+0x42d/0x7c0 net/core/skbuff.c:611
skb_release_all+0x4d/0x60 net/core/skbuff.c:665
__kfree_skb net/core/skbuff.c:679 [inline]
kfree_skb net/core/skbuff.c:697 [inline]
kfree_skb+0x101/0x3c0 net/core/skbuff.c:691
bcsp_close+0xc7/0x130 drivers/bluetooth/hci_bcsp.c:748
hci_uart_tty_close+0x21e/0x280 drivers/bluetooth/hci_ldisc.c:548
tty_ldisc_close.isra.0+0x119/0x1a0 drivers/tty/tty_ldisc.c:494
tty_ldisc_kill+0x9c/0x160 drivers/tty/tty_ldisc.c:642
tty_ldisc_release+0xe9/0x2b0 drivers/tty/tty_ldisc.c:814
tty_release_struct+0x1b/0x50 drivers/tty/tty_io.c:1612
tty_release+0xbcb/0xe90 drivers/tty/tty_io.c:1785
__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
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x904/0x2e60 kernel/exit.c:817
do_group_exit+0x135/0x360 kernel/exit.c:921
get_signal+0x47c/0x2500 kernel/signal.c:2734
do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815
exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:159
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446809
Code: Bad RIP value.
RSP: 002b:00007feedabcfdb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffe00 RBX: 00000000006dbc38 RCX: 0000000000446809
RDX: 000000000000005b RSI: 0000000020000080 RDI: 0000000000000007
RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 00007fff8abe57cf R14: 00007feedabd09c0 R15: 0000000000000000

Allocated by task 9184:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc mm/kasan/common.c:510 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
__do_kmalloc_node mm/slab.c:3615 [inline]
__kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3629
__kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:141
__alloc_skb+0x10b/0x5e0 net/core/skbuff.c:209
alloc_skb include/linux/skbuff.h:1049 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
bcsp_recv+0x8c1/0x13a0 drivers/bluetooth/hci_bcsp.c:670
hci_uart_tty_receive+0x279/0x6e0 drivers/bluetooth/hci_ldisc.c:613
tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:465
tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
receive_buf drivers/tty/tty_buffer.c:481 [inline]
flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:533
process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 9184:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
kasan_set_free_info mm/kasan/common.c:332 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
__cache_free mm/slab.c:3425 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3756
skb_free_head+0x93/0xb0 net/core/skbuff.c:591
skb_release_data+0x42d/0x7c0 net/core/skbuff.c:611
skb_release_all+0x4d/0x60 net/core/skbuff.c:665
__kfree_skb net/core/skbuff.c:679 [inline]
kfree_skb net/core/skbuff.c:697 [inline]
kfree_skb+0x101/0x3c0 net/core/skbuff.c:691
bcsp_recv+0x2d8/0x13a0 drivers/bluetooth/hci_bcsp.c:608
hci_uart_tty_receive+0x279/0x6e0 drivers/bluetooth/hci_ldisc.c:613
tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:465
tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
receive_buf drivers/tty/tty_buffer.c:481 [inline]
flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:533
process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8880946e4000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 0 bytes inside of
8192-byte region [ffff8880946e4000, ffff8880946e6000)
The buggy address belongs to the page:
page:ffffea000251b900 refcount:1 mapcount:0 mapping:ffff8880aa4021c0 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00024a2e08 ffffea0002631c08 ffff8880aa4021c0
raw: 0000000000000000 ffff8880946e4000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880946e3f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880946e3f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff8880946e4000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8880946e4080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880946e4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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 syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Next message: Gabriela Bittencourt: "[PATCH v2] drm/doc: Adding VKMS module description and use to "Testing and Validation""
Previous message: Joe Perches: "Re: [PATCH 3.16 47/47] KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed"
Next in thread: Tomas Bortoli: "[PATCH] Fix invalid-free in bcsp_close()"
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