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Subject: Re: [PATCH] Bluetooth: Fix use after free in hci_send_acl
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20220311211933.3285806-1-luiz.dentz@gmail.com>
Date:   Mon, 14 Mar 2022 16:25:09 +0100
Cc:     linux-bluetooth@vger.kernel.org
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Message-Id: <4307603B-96C6-45FA-8CCF-B6626989E944@holtmann.org>
References: <20220311211933.3285806-1-luiz.dentz@gmail.com>
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Precedence: bulk

Hi Luiz,

> This fixes the following trace caused by receiving
> HCI_EV_DISCONN_PHY_LINK_COMPLETE which does call hci_conn_del without
> first checking if conn->type is in fact AMP_LINK and in case it is
> do properly cleanup upper layers with hci_disconn_cfm:
> 
> ==================================================================
>    BUG: KASAN: use-after-free in hci_send_acl+0xaba/0xc50
>    Read of size 8 at addr ffff88800e404818 by task bluetoothd/142
> 
>    CPU: 0 PID: 142 Comm: bluetoothd Not tainted
>    5.17.0-rc5-00006-gda4022eeac1a #7
>    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>    rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
>    Call Trace:
>     <TASK>
>     dump_stack_lvl+0x45/0x59
>     print_address_description.constprop.0+0x1f/0x150
>     kasan_report.cold+0x7f/0x11b
>     hci_send_acl+0xaba/0xc50
>     l2cap_do_send+0x23f/0x3d0
>     l2cap_chan_send+0xc06/0x2cc0
>     l2cap_sock_sendmsg+0x201/0x2b0
>     sock_sendmsg+0xdc/0x110
>     sock_write_iter+0x20f/0x370
>     do_iter_readv_writev+0x343/0x690
>     do_iter_write+0x132/0x640
>     vfs_writev+0x198/0x570
>     do_writev+0x202/0x280
>     do_syscall_64+0x38/0x90
>     entry_SYSCALL_64_after_hwframe+0x44/0xae
>    RSP: 002b:00007ffce8a099b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
>    Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3
>    0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 14 00 00 00 0f 05
>    <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
>    RDX: 0000000000000001 RSI: 00007ffce8a099e0 RDI: 0000000000000015
>    RAX: ffffffffffffffda RBX: 00007ffce8a099e0 RCX: 00007f788fc3cf77
>    R10: 00007ffce8af7080 R11: 0000000000000246 R12: 000055e4ccf75580
>    RBP: 0000000000000015 R08: 0000000000000002 R09: 0000000000000001
>    </TASK>
>    R13: 000055e4ccf754a0 R14: 000055e4ccf75cd0 R15: 000055e4ccf4a6b0
> 
>    Allocated by task 45:
>        kasan_save_stack+0x1e/0x40
>        __kasan_kmalloc+0x81/0xa0
>        hci_chan_create+0x9a/0x2f0
>        l2cap_conn_add.part.0+0x1a/0xdc0
>        l2cap_connect_cfm+0x236/0x1000
>        le_conn_complete_evt+0x15a7/0x1db0
>        hci_le_conn_complete_evt+0x226/0x2c0
>        hci_le_meta_evt+0x247/0x450
>        hci_event_packet+0x61b/0xe90
>        hci_rx_work+0x4d5/0xc50
>        process_one_work+0x8fb/0x15a0
>        worker_thread+0x576/0x1240
>        kthread+0x29d/0x340
>        ret_from_fork+0x1f/0x30
> 
>    Freed by task 45:
>        kasan_save_stack+0x1e/0x40
>        kasan_set_track+0x21/0x30
>        kasan_set_free_info+0x20/0x30
>        __kasan_slab_free+0xfb/0x130
>        kfree+0xac/0x350
>        hci_conn_cleanup+0x101/0x6a0
>        hci_conn_del+0x27e/0x6c0
>        hci_disconn_phylink_complete_evt+0xe0/0x120
>        hci_event_packet+0x812/0xe90
>        hci_rx_work+0x4d5/0xc50
>        process_one_work+0x8fb/0x15a0
>        worker_thread+0x576/0x1240
>        kthread+0x29d/0x340
>        ret_from_fork+0x1f/0x30
> 
>    The buggy address belongs to the object at ffff88800c0f0500
>    The buggy address is located 24 bytes inside of
>    which belongs to the cache kmalloc-128 of size 128
>    The buggy address belongs to the page:
>    128-byte region [ffff88800c0f0500, ffff88800c0f0580)
>    flags: 0x100000000000200(slab|node=0|zone=1)
>    page:00000000fe45cd86 refcount:1 mapcount:0
>    mapping:0000000000000000 index:0x0 pfn:0xc0f0
>    raw: 0000000000000000 0000000080100010 00000001ffffffff
>    0000000000000000
>    raw: 0100000000000200 ffffea00003a2c80 dead000000000004
>    ffff8880078418c0
>    page dumped because: kasan: bad access detected
>    ffff88800c0f0400: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
>    Memory state around the buggy address:
>> ffff88800c0f0500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>    ffff88800c0f0480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>    ffff88800c0f0580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>                                ^
>    ==================================================================
>    ffff88800c0f0600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> 
> Reported-by: Sönke Huster <soenke.huster@eknoes.de>
> Tested-by: Sönke Huster <soenke.huster@eknoes.de>
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> ---
> net/bluetooth/hci_event.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel