[PATCH 1/1] NFC: Fix the number of pipes

[PATCH 1/1] NFC: Fix the number of pipes

[Suren Baghdasaryan]

According to ETSI TS 102 622 specification chapter 4.4 pipe identifier
is 7 bits long which allows for 128 unique pipe IDs. Because
NFC_HCI_MAX_PIPES is used as the number of pipes supported and not
as the max pipe ID, its value should be 128 instead of 127.

nfc_hci_recv_from_llc extracts pipe ID from packet header using
NFC_HCI_FRAGMENT(0x7F) mask which allows for pipe ID value of 127.
Same happens when NCI_HCP_MSG_GET_PIPE() is being used. With
pipes array having only 127 elements and pipe ID of 127 the OOB memory
access will result.

Suggested-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Suren Baghdasaryan <surenb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
---
 include/net/nfc/hci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/nfc/hci.h b/include/net/nfc/hci.h
index 316694dafa5b..008f466d1da7 100644
--- a/include/net/nfc/hci.h
+++ b/include/net/nfc/hci.h
@@ -87,7 +87,7 @@ struct nfc_hci_pipe {
  * According to specification 102 622 chapter 4.4 Pipes,
  * the pipe identifier is 7 bits long.
  */
-#define NFC_HCI_MAX_PIPES		127
+#define NFC_HCI_MAX_PIPES		128
 struct nfc_hci_init_data {
 	u8 gate_count;
 	struct nfc_hci_gate gates[NFC_HCI_MAX_CUSTOM_GATES];
-- 
2.18.0.865.gffc8e1a3cd6-goog

Re: [PATCH 1/1] NFC: Fix the number of pipes

[Kees Cook]

On Tue, Aug 14, 2018 at 3:35 PM, Suren Baghdasaryan <surenb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:
> According to ETSI TS 102 622 specification chapter 4.4 pipe identifier
> is 7 bits long which allows for 128 unique pipe IDs. Because
> NFC_HCI_MAX_PIPES is used as the number of pipes supported and not
> as the max pipe ID, its value should be 128 instead of 127.
>
> nfc_hci_recv_from_llc extracts pipe ID from packet header using
> NFC_HCI_FRAGMENT(0x7F) mask which allows for pipe ID value of 127.
> Same happens when NCI_HCP_MSG_GET_PIPE() is being used. With
> pipes array having only 127 elements and pipe ID of 127 the OOB memory
> access will result.
>
> Suggested-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Suren Baghdasaryan <surenb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

Reviewed-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>

-Kees

> ---
>  include/net/nfc/hci.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/net/nfc/hci.h b/include/net/nfc/hci.h
> index 316694dafa5b..008f466d1da7 100644
> --- a/include/net/nfc/hci.h
> +++ b/include/net/nfc/hci.h
> @@ -87,7 +87,7 @@ struct nfc_hci_pipe {
>   * According to specification 102 622 chapter 4.4 Pipes,
>   * the pipe identifier is 7 bits long.
>   */
> -#define NFC_HCI_MAX_PIPES              127
> +#define NFC_HCI_MAX_PIPES              128
>  struct nfc_hci_init_data {
>         u8 gate_count;
>         struct nfc_hci_gate gates[NFC_HCI_MAX_CUSTOM_GATES];
> --
> 2.18.0.865.gffc8e1a3cd6-goog
>



-- 
Kees Cook
Pixel Security