Re: [PATCH v2] Bluetooth: hci: fix null-ptr-deref in hci_read_supported_codecs

[Luiz Augusto von Dentz]

Hi Sungwoo,

On Mon, Oct 28, 2024 at 10:41 PM Sungwoo Kim <iam@xxxxxxxxxxxx> wrote:
>
> Dear Luiz, could you review this? This bug and fix are still valid but
> have been forgotten for some reason.

Please resend.

> On Sat, Jul 6, 2024 at 6:53 PM Sungwoo Kim <iam@xxxxxxxxxxxx> wrote:
> >
> > __hci_cmd_sync_sk() returns NULL if a command returns a status event
> > as there are no parameters.
> > Fix __hci_cmd_sync_sk() to not return NULL.
> >
> > KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077]
> > CPU: 1 PID: 2000 Comm: kworker/u9:5 Not tainted 6.9.0-ga6bcb805883c-dirty #10
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> > Workqueue: hci7 hci_power_on
> > RIP: 0010:hci_read_supported_codecs+0xb9/0x870 net/bluetooth/hci_codec.c:138
> > Code: 08 48 89 ef e8 b8 c1 8f fd 48 8b 75 00 e9 96 00 00 00 49 89 c6 48 ba 00 00 00 00 00 fc ff df 4c 8d 60 70 4c 89 e3 48 c1 eb 03 <0f> b6 04 13 84 c0 0f 85 82 06 00 00 41 83 3c 24 02 77 0a e8 bf 78
> > RSP: 0018:ffff888120bafac8 EFLAGS: 00010212
> > RAX: 0000000000000000 RBX: 000000000000000e RCX: ffff8881173f0040
> > RDX: dffffc0000000000 RSI: ffffffffa58496c0 RDI: ffff88810b9ad1e4
> > RBP: ffff88810b9ac000 R08: ffffffffa77882a7 R09: 1ffffffff4ef1054
> > R10: dffffc0000000000 R11: fffffbfff4ef1055 R12: 0000000000000070
> > R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810b9ac000
> > FS:  0000000000000000(0000) GS:ffff8881f6c00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007f6ddaa3439e CR3: 0000000139764003 CR4: 0000000000770ef0
> > PKRU: 55555554
> > Call Trace:
> >  <TASK>
> >  hci_read_local_codecs_sync net/bluetooth/hci_sync.c:4546 [inline]
> >  hci_init_stage_sync net/bluetooth/hci_sync.c:3441 [inline]
> >  hci_init4_sync net/bluetooth/hci_sync.c:4706 [inline]
> >  hci_init_sync net/bluetooth/hci_sync.c:4742 [inline]
> >  hci_dev_init_sync net/bluetooth/hci_sync.c:4912 [inline]
> >  hci_dev_open_sync+0x19a9/0x2d30 net/bluetooth/hci_sync.c:4994
> >  hci_dev_do_open net/bluetooth/hci_core.c:483 [inline]
> >  hci_power_on+0x11e/0x560 net/bluetooth/hci_core.c:1015
> >  process_one_work kernel/workqueue.c:3267 [inline]
> >  process_scheduled_works+0x8ef/0x14f0 kernel/workqueue.c:3348
> >  worker_thread+0x91f/0xe50 kernel/workqueue.c:3429
> >  kthread+0x2cb/0x360 kernel/kthread.c:388
> >  ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
> >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> >
> > Fixes: abfeea476c68 ("Bluetooth: hci_sync: Convert MGMT_OP_START_DISCOVERY")
> >
> > Signed-off-by: Sungwoo Kim <iam@xxxxxxxxxxxx>
> > ---
> > v1 -> v2: make __hci_cmd_sync_sk() not return NULL
> >
> >  net/bluetooth/hci_sync.c | 18 +++++++++++-------
> >  1 file changed, 11 insertions(+), 7 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> > index 76b283b8e..c4e4abc6e 100644
> > --- a/net/bluetooth/hci_sync.c
> > +++ b/net/bluetooth/hci_sync.c
> > @@ -201,6 +201,12 @@ struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
> >                 return ERR_PTR(err);
> >         }
> >
> > +       /* If command return a status event skb will be set to NULL as there are
> > +        * no parameters.
> > +        */
> > +       if (!skb)
> > +               return ERR_PTR(-ENODATA);
> > +
> >         return skb;
> >  }
> >  EXPORT_SYMBOL(__hci_cmd_sync_sk);
> > @@ -250,6 +256,11 @@ int __hci_cmd_sync_status_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
> >         u8 status;
> >
> >         skb = __hci_cmd_sync_sk(hdev, opcode, plen, param, event, timeout, sk);
> > +
> > +       /* If command return a status event, skb will be set to -ENODATA */
> > +       if (skb == ERR_PTR(-ENODATA))
> > +               return 0;
> > +
> >         if (IS_ERR(skb)) {
> >                 if (!event)
> >                         bt_dev_err(hdev, "Opcode 0x%4.4x failed: %ld", opcode,
> > @@ -257,13 +268,6 @@ int __hci_cmd_sync_status_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
> >                 return PTR_ERR(skb);
> >         }
> >
> > -       /* If command return a status event skb will be set to NULL as there are
> > -        * no parameters, in case of failure IS_ERR(skb) would have be set to
> > -        * the actual error would be found with PTR_ERR(skb).
> > -        */
> > -       if (!skb)
> > -               return 0;
> > -
> >         status = skb->data[0];
> >
> >         kfree_skb(skb);
> > --
> > 2.34.1
> >



-- 
Luiz Augusto von Dentz