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Message-ID: <82554b3b-1b0e-6202-bb97-d969997c10b2@gmail.com>
Date: Thu, 29 Jul 2021 20:05:07 +0800
From: Phi Nguyen <phind.uet@...il.com>
To: Marcel Holtmann <marcel@...tmann.org>
Cc: syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
Johan Hedberg <johan.hedberg@...il.com>,
linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: memory leak in h4_recv_buf
On 7/29/2021 7:44 PM, Marcel Holtmann wrote:
> Hi Phi,
>
>>> Hello,
>>> syzbot found the following crash on:
>>> HEAD commit: abf02e29 Merge tag 'pm-5.2-rc6' of
>>> git://git.kernel.org/pu <http://git.kernel.org/pu>..
>>> git tree: upstream
>>> console output:
>>> https://syzkaller.appspot.com/x/log.txt?x=1054e6b2a00000
>>> <https://syzkaller.appspot.com/x/log.txt?x=1054e6b2a00000>
>>> kernel config:
>>> https://syzkaller.appspot.com/x/.config?x=56f1da14935c3cce
>>> <https://syzkaller.appspot.com/x/.config?x=56f1da14935c3cce>
>>> dashboard link:
>>> https://syzkaller.appspot.com/bug?extid=97388eb9d31b997fe1d0
>>> <https://syzkaller.appspot.com/bug?extid=97388eb9d31b997fe1d0>
>>> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
>>> syz repro:
>>> https://syzkaller.appspot.com/x/repro.syz?x=1073d8aaa00000
>>> <https://syzkaller.appspot.com/x/repro.syz?x=1073d8aaa00000>
>>> C reproducer:
>>> https://syzkaller.appspot.com/x/repro.c?x=17b36fbea00000
>>> <https://syzkaller.appspot.com/x/repro.c?x=17b36fbea00000>
>>> IMPORTANT: if you fix the bug, please add the following tag to the
>>> commit:
>>> Reported-by: syzbot+97388e...@...kaller.appspotmail.com
>>> program
>>> BUG: memory leak
>>> unreferenced object 0xffff88810991fa00 (size 224):
>>> comm "syz-executor739", pid 7080, jiffies 4294949854 (age 18.640s)
>>> hex dump (first 32 bytes):
>>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
>>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
>>> backtrace:
>>> [<00000000da42c09f>] kmemleak_alloc_recursive
>>> include/linux/kmemleak.h:43 [inline]
>>> [<00000000da42c09f>] slab_post_alloc_hook mm/slab.h:439 [inline]
>>> [<00000000da42c09f>] slab_alloc_node mm/slab.c:3269 [inline]
>>> [<00000000da42c09f>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
>>> [<00000000f6fbcf84>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:194
>>> [<00000000ea93fc4c>] alloc_skb include/linux/skbuff.h:1054 [inline]
>>> [<00000000ea93fc4c>] bt_skb_alloc include/net/bluetooth/bluetooth.h:339
>>> [inline]
>>> [<00000000ea93fc4c>] h4_recv_buf+0x26d/0x450
>>> drivers/bluetooth/hci_h4.c:182
>>> [<00000000e0312475>] h4_recv+0x51/0xb0 drivers/bluetooth/hci_h4.c:116
>>> [<00000000ebf11fab>] hci_uart_tty_receive+0xba/0x200
>>> drivers/bluetooth/hci_ldisc.c:592
>>> [<0000000095e1216e>] tiocsti drivers/tty/tty_io.c:2195 [inline]
>>> [<0000000095e1216e>] tty_ioctl+0x81c/0xa30 drivers/tty/tty_io.c:2571
>>> [<000000009fa523f0>] vfs_ioctl fs/ioctl.c:46 [inline]
>>> [<000000009fa523f0>] file_ioctl fs/ioctl.c:509 [inline]
>>> [<000000009fa523f0>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
>>> [<000000000cebb5d9>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
>>> [<000000001630008a>] __do_sys_ioctl fs/ioctl.c:720 [inline]
>>> [<000000001630008a>] __se_sys_ioctl fs/ioctl.c:718 [inline]
>>> [<000000001630008a>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718
>>> [<00000000c62091e3>] do_syscall_64+0x76/0x1a0
>>> arch/x86/entry/common.c:301
>>> [<000000005c213625>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> BUG: memory leak
>>> unreferenced object 0xffff8881204f4400 (size 1024):
>>> comm "syz-executor739", pid 7080, jiffies 4294949854 (age 18.640s)
>>> hex dump (first 32 bytes):
>>> 6c 69 62 75 64 65 76 00 fe ed ca fe 28 00 00 00 libudev.....(...
>>> 28 00 00 00 a0 00 00 00 52 ca da 77 00 00 00 00 (.......R..w....
>>> backtrace:
>>> [<0000000034504843>] kmemleak_alloc_recursive
>>> include/linux/kmemleak.h:43 [inline]
>>> [<0000000034504843>] slab_post_alloc_hook mm/slab.h:439 [inline]
>>> [<0000000034504843>] slab_alloc_node mm/slab.c:3269 [inline]
>>> [<0000000034504843>] kmem_cache_alloc_node_trace+0x15b/0x2a0
>>> mm/slab.c:3597
>>> [<0000000056d30eb5>] __do_kmalloc_node mm/slab.c:3619 [inline]
>>> [<0000000056d30eb5>] __kmalloc_node_track_caller+0x38/0x50
>>> mm/slab.c:3634
>>> [<00000000df40176c>] __kmalloc_reserve.isra.0+0x40/0xb0
>>> net/core/skbuff.c:138
>>> [<0000000035340e64>] __alloc_skb+0xa0/0x210 net/core/skbuff.c:206
>>> [<00000000ea93fc4c>] alloc_skb include/linux/skbuff.h:1054 [inline]
>>> [<00000000ea93fc4c>] bt_skb_alloc include/net/bluetooth/bluetooth.h:339
>>> [inline]
>>> [<00000000ea93fc4c>] h4_recv_buf+0x26d/0x450
>>> drivers/bluetooth/hci_h4.c:182
>>> [<00000000e0312475>] h4_recv+0x51/0xb0 drivers/bluetooth/hci_h4.c:116
>>> [<00000000ebf11fab>] hci_uart_tty_receive+0xba/0x200
>>> drivers/bluetooth/hci_ldisc.c:592
>>> [<0000000095e1216e>] tiocsti drivers/tty/tty_io.c:2195 [inline]
>>> [<0000000095e1216e>] tty_ioctl+0x81c/0xa30 drivers/tty/tty_io.c:2571
>>> [<000000009fa523f0>] vfs_ioctl fs/ioctl.c:46 [inline]
>>> [<000000009fa523f0>] file_ioctl fs/ioctl.c:509 [inline]
>>> [<000000009fa523f0>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
>>> [<000000000cebb5d9>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
>>> [<000000001630008a>] __do_sys_ioctl fs/ioctl.c:720 [inline]
>>> [<000000001630008a>] __se_sys_ioctl fs/ioctl.c:718 [inline]
>>> [<000000001630008a>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718
>>> [<00000000c62091e3>] do_syscall_64+0x76/0x1a0
>>> arch/x86/entry/common.c:301
>>> [<000000005c213625>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> ---
>>> This bug is generated by a bot. It may contain errors.
>>> See https://goo.gl/tpsmEJ <https://goo.gl/tpsmEJ> for more
>>> information about syzbot.
>>> syzbot engineers can be reached at syzk...@...glegroups.com.
>>> syzbot will keep track of this bug report. See:
>>> https://goo.gl/tpsmEJ#status <https://goo.gl/tpsmEJ#status> for how
>>> to communicate with syzbot.
>>> syzbot can test patches for this bug, for details see:
>>> https://goo.gl/tpsmEJ#testing-patches
>>> <https://goo.gl/tpsmEJ#testing-patches>
>>> --
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>>> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/d71a274f-fdeb-4da1-898e-06f6944e04dan%40googlegroups.com <https://groups.google.com/d/msgid/syzkaller-bugs/d71a274f-fdeb-4da1-898e-06f6944e04dan%40googlegroups.com?utm_medium=email&utm_source=footer>.
>>
>> The reason of this memory leak is tty_ldisc_receive_buf() and tiocsti()
>> can access the h4->rx_skb concurrently by calling
>> hci_uart_tty_receive(), so the rx_skb be overwritten without
>> deallocating. There used to be an spin_lock in hci_uart_tty_receive(),
>> but it was removed by commit 7649ffaff1cfe(Bluetooth: Remove useless
>> rx_lock spinlock).
>
> I don’t have that commit in my Linus’ tree. Where is it?
>
>> The commit message claims that hci_uart_tty_receive() was only called by
>> flush_to_ldisc(), but it seems incorrect.
>
> That seems to be a larger problem in the TTY layer if its contract with its users have changed.
>
> Regards
>
> Marcel
>
Hi Marcel,
It was my typo, the git hash should be 7649faff1cfe4.
Regards,
Phi.
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