[PATCH 1/3 v2] staging: r8188eu: Drop get_recvframe_data()

[Kees Cook]

When building with -Warray-bounds, the following warning is emitted:

In file included from ./include/linux/string.h:253,
                 from ./arch/x86/include/asm/page_32.h:22,
                 from ./arch/x86/include/asm/page.h:14,
                 from ./arch/x86/include/asm/thread_info.h:12,
                 from ./include/linux/thread_info.h:60,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/rcupdate.h:27,
                 from ./include/linux/rculist.h:11,
                 from ./include/linux/sched/signal.h:5,
                 from ./drivers/staging/rtl8723bs/include/drv_types.h:17,
                 from drivers/staging/rtl8723bs/core/rtw_recv.c:7:
In function 'memcpy',
    inlined from 'wlanhdr_to_ethhdr' at drivers/staging/rtl8723bs/core/rtw_recv.c:1554:2:
./include/linux/fortify-string.h:41:33: warning: '__builtin_memcpy' offset [0, 5] is out of the bounds [0, 0] [-Warray-bounds]
   41 | #define __underlying_memcpy     __builtin_memcpy
      |                                 ^

This is because the compiler sees it is possible for "ptr" to be a NULL
value, and concludes that it has zero size and attempts to copy to it
would overflow. Instead, remove the get_recvframe_data() entirely, as
it's not possible for this to ever be NULL.

Additionally add missing NULL checks after recvframe_pull() (which are
present in the rtl8712 driver).

Cc: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Cc: Phillip Potter <phil@xxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Straube <straube.linux@xxxxxxxxx>
Cc: Fabio Aiuto <fabioaiuto83@xxxxxxxxx>
Cc: linux-staging@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/staging/r8188eu/core/rtw_recv.c       | 6 +++++-
 drivers/staging/r8188eu/hal/rtl8188e_rxdesc.c | 4 +---
 drivers/staging/r8188eu/include/rtw_recv.h    | 9 ---------
 3 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_recv.c b/drivers/staging/r8188eu/core/rtw_recv.c
index 51a13262a226..946e659ae97a 100644
--- a/drivers/staging/r8188eu/core/rtw_recv.c
+++ b/drivers/staging/r8188eu/core/rtw_recv.c
@@ -1188,7 +1188,7 @@ static int wlanhdr_to_ethhdr(struct recv_frame *precvframe)
 	struct adapter			*adapter = precvframe->adapter;
 	struct mlme_priv	*pmlmepriv = &adapter->mlmepriv;
 
-	u8	*ptr = get_recvframe_data(precvframe); /*  point to frame_ctrl field */
+	u8	*ptr = precvframe->rx_data; /*  point to frame_ctrl field */
 	struct rx_pkt_attrib *pattrib = &precvframe->attrib;
 
 	if (pattrib->encrypt)
@@ -1223,10 +1223,14 @@ static int wlanhdr_to_ethhdr(struct recv_frame *precvframe)
 		eth_type = 0x8712;
 		/*  append rx status for mp test packets */
 		ptr = recvframe_pull(precvframe, (rmv_len - sizeof(struct ethhdr) + 2) - 24);
+		if (!ptr)
+			return _FAIL;
 		memcpy(ptr, get_rxmem(precvframe), 24);
 		ptr += 24;
 	} else {
 		ptr = recvframe_pull(precvframe, (rmv_len - sizeof(struct ethhdr) + (bsnaphdr ? 2 : 0)));
+		if (!ptr)
+			return _FAIL;
 	}
 
 	memcpy(ptr, pattrib->dst, ETH_ALEN);
diff --git a/drivers/staging/r8188eu/hal/rtl8188e_rxdesc.c b/drivers/staging/r8188eu/hal/rtl8188e_rxdesc.c
index 90d426199f52..bf93ff3af140 100644
--- a/drivers/staging/r8188eu/hal/rtl8188e_rxdesc.c
+++ b/drivers/staging/r8188eu/hal/rtl8188e_rxdesc.c
@@ -128,7 +128,7 @@ void update_recvframe_phyinfo_88e(struct recv_frame *precvframe, struct phy_stat
 	struct rx_pkt_attrib *pattrib = &precvframe->attrib;
 	struct hal_data_8188e *pHalData = &padapter->haldata;
 	struct phy_info *pPHYInfo  = &pattrib->phy_info;
-	u8 *wlanhdr;
+	u8 *wlanhdr = precvframe->rx_data;
 	struct odm_per_pkt_info	pkt_info;
 	u8 *sa = NULL;
 	struct sta_priv *pstapriv;
@@ -138,8 +138,6 @@ void update_recvframe_phyinfo_88e(struct recv_frame *precvframe, struct phy_stat
 	pkt_info.bPacketToSelf = false;
 	pkt_info.bPacketBeacon = false;
 
-	wlanhdr = get_recvframe_data(precvframe);
-
 	pkt_info.bPacketMatchBSSID = ((!IsFrameTypeCtrl(wlanhdr)) &&
 		!pattrib->icv_err && !pattrib->crc_err &&
 		!memcmp(get_hdr_bssid(wlanhdr),
diff --git a/drivers/staging/r8188eu/include/rtw_recv.h b/drivers/staging/r8188eu/include/rtw_recv.h
index b43a46887343..920f33235e00 100644
--- a/drivers/staging/r8188eu/include/rtw_recv.h
+++ b/drivers/staging/r8188eu/include/rtw_recv.h
@@ -296,15 +296,6 @@ static inline u8 *get_rx_status(struct recv_frame *precvframe)
 	return get_rxmem(precvframe);
 }
 
-static inline u8 *get_recvframe_data(struct recv_frame *precvframe)
-{
-	/* always return rx_data */
-	if (precvframe == NULL)
-		return NULL;
-
-	return precvframe->rx_data;
-}
-
 static inline u8 *recvframe_push(struct recv_frame *precvframe, int sz)
 {
 	/*  append data before rx_data */
-- 
2.30.2