[PATCH v4] Bluetooth: btmtk: Fix null pointer when processing coredump

[Chris Lu (陸稚泓)]

On Wed, 2023-07-12 at 13:29 -0700, Luiz Augusto von Dentz wrote:
>  	 
> External email : Please do not click links or open attachments until
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>  Hi Chris,
> 
> On Wed, Jul 12, 2023 at 6:03 AM Chris Lu <chris.lu at mediatek.com>
> wrote:
> >
> > There may be a potential null pointer risk if offset value is
> > less than 0 when doing memcmp in btmtk_process_coredump().
> > Check offset is valid before doing memcmp.
> >
> > Signed-off-by: Chris Lu <chris.lu at mediatek.com>
> > Co-developed-by: Sean Wang <sean.wang at mediatek.com>
> > Signed-off-by: Sean Wang <sean.wang at mediatek.com>
> 
> You should probably include the Fixes tag of the patch that
> introduced
> the problem.
> 
Hi Luiz,

Thanks for reminding, I'll update Bug ad fixs info in commit message
and send the v5 patch.

BRs,
Chris

> > ---
> > v2: fix typo
> > v3: fix bot checking error
> > v4: reduce variable 'offset' declaration in v3
> > ---
> >  drivers/bluetooth/btmtk.c | 12 ++++++------
> >  drivers/bluetooth/btmtk.h |  1 +
> >  2 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
> > index 786f775196ae..9cc789272ab7 100644
> > --- a/drivers/bluetooth/btmtk.c
> > +++ b/drivers/bluetooth/btmtk.c
> > @@ -395,12 +395,12 @@ int btmtk_process_coredump(struct hci_dev
> *hdev, struct sk_buff *skb)
> >
> >                 /* Mediatek coredump data would be more than
> MTK_COREDUMP_NUM */
> >                 if (data->cd_info.cnt > MTK_COREDUMP_NUM &&
> > -                   skb->len > sizeof(MTK_COREDUMP_END) &&
> > -                   !memcmp((char *)&skb->data[skb->len -
> sizeof(MTK_COREDUMP_END)],
> > -                           MTK_COREDUMP_END,
> sizeof(MTK_COREDUMP_END) - 1)) {
> > -                       bt_dev_info(hdev, "Mediatek coredump end");
> > -                       hci_devcd_complete(hdev);
> > -               }
> > +                   skb->len > MTK_COREDUMP_END_LEN)
> > +                       if (!memcmp((char *)&skb->data[skb->len -
> MTK_COREDUMP_END_LEN],
> > +                           MTK_COREDUMP_END, MTK_COREDUMP_END_LEN
> - 1)) {
> > +                               bt_dev_info(hdev, "Mediatek
> coredump end");
> > +                               hci_devcd_complete(hdev);
> > +                       }
> >
> >                 break;
> >         }
> > diff --git a/drivers/bluetooth/btmtk.h b/drivers/bluetooth/btmtk.h
> > index 68309dfe076a..56f5502baadf 100644
> > --- a/drivers/bluetooth/btmtk.h
> > +++ b/drivers/bluetooth/btmtk.h
> > @@ -24,6 +24,7 @@
> >
> >  #define MTK_COREDUMP_SIZE              (1024 * 1000)
> >  #define MTK_COREDUMP_END               "coredump end"
> > +#define MTK_COREDUMP_END_LEN           (sizeof(MTK_COREDUMP_END))
> >  #define MTK_COREDUMP_NUM               255
> >
> >  enum {
> > --
> > 2.18.0
> >
> 
> 
> -- 
> Luiz Augusto von Dentz