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

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

Posted by Chris Lu 1 year, 2 months ago

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@mediatek.com>
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
---
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

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

Posted by Luiz Augusto von Dentz 1 year, 2 months ago

Hi Chris,

On Wed, Jul 12, 2023 at 6:03 AM Chris Lu <chris.lu@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@mediatek.com>
> Co-developed-by: Sean Wang <sean.wang@mediatek.com>
> Signed-off-by: Sean Wang <sean.wang@mediatek.com>

You should probably include the Fixes tag of the patch that introduced
the problem.

> ---
> 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

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

Posted by Chris Lu (陸稚泓) 1 year, 2 months ago

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
> you have verified the sender or the content.
>  Hi Chris,
> 
> On Wed, Jul 12, 2023 at 6:03 AM Chris Lu <chris.lu@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@mediatek.com>
> > Co-developed-by: Sean Wang <sean.wang@mediatek.com>
> > Signed-off-by: Sean Wang <sean.wang@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