diff mbox series

mwifiex: avoid null-pointer-subtraction warning

Message ID 20210927121656.940304-1-arnd@kernel.org (mailing list archive)
State Awaiting Upstream
Delegated to: Netdev Maintainers
Headers show
Series mwifiex: avoid null-pointer-subtraction warning | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Arnd Bergmann Sept. 27, 2021, 12:16 p.m. UTC 
From: Arnd Bergmann <arnd@arndb.de>

clang complains about some NULL pointer arithmetic in this driver:

drivers/net/wireless/marvell/mwifiex/sta_tx.c:65:59: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
        pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
                                                                 ^
drivers/net/wireless/marvell/mwifiex/uap_txrx.c:478:53: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
        pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &

Rework that expression to do the same thing using a uintptr_t.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/wireless/marvell/mwifiex/sta_tx.c   | 4 ++--
 drivers/net/wireless/marvell/mwifiex/uap_txrx.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

Comments

Kalle Valo Sept. 28, 2021, 6:43 a.m. UTC | #1 
Arnd Bergmann <arnd@kernel.org> writes:

> From: Arnd Bergmann <arnd@arndb.de>
>
> clang complains about some NULL pointer arithmetic in this driver:
>
> drivers/net/wireless/marvell/mwifiex/sta_tx.c:65:59: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>         pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
>                                                                  ^
> drivers/net/wireless/marvell/mwifiex/uap_txrx.c:478:53: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>         pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &
>
> Rework that expression to do the same thing using a uintptr_t.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

I'll queue this to v5.15.
Kalle Valo Sept. 28, 2021, 2:42 p.m. UTC | #2 
Arnd Bergmann <arnd@kernel.org> wrote:

> From: Arnd Bergmann <arnd@arndb.de>
> 
> clang complains about some NULL pointer arithmetic in this driver:
> 
> drivers/net/wireless/marvell/mwifiex/sta_tx.c:65:59: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>         pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
>                                                                  ^
> drivers/net/wireless/marvell/mwifiex/uap_txrx.c:478:53: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>         pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &
> 
> Rework that expression to do the same thing using a uintptr_t.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Patch applied to wireless-drivers.git, thanks.

603a1621caa0 mwifiex: avoid null-pointer-subtraction warning
diff mbox series

Patch

diff --git a/drivers/net/wireless/marvell/mwifiex/sta_tx.c b/drivers/net/wireless/marvell/mwifiex/sta_tx.c
index 241305377e20..a9b5eb992220 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_tx.c
+++ b/drivers/net/wireless/marvell/mwifiex/sta_tx.c
@@ -62,8 +62,8 @@  void *mwifiex_process_sta_txpd(struct mwifiex_private *priv,
 
 	pkt_type = mwifiex_is_skb_mgmt_frame(skb) ? PKT_TYPE_MGMT : 0;
 
-	pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
-			 NULL) & (MWIFIEX_DMA_ALIGN_SZ - 1);
+	pad = ((uintptr_t)skb->data - (sizeof(*local_tx_pd) + hroom)) &
+	       (MWIFIEX_DMA_ALIGN_SZ - 1);
 	skb_push(skb, sizeof(*local_tx_pd) + pad);
 
 	local_tx_pd = (struct txpd *) skb->data;
diff --git a/drivers/net/wireless/marvell/mwifiex/uap_txrx.c b/drivers/net/wireless/marvell/mwifiex/uap_txrx.c
index 9bbdb8dfce62..245ff644f81e 100644
--- a/drivers/net/wireless/marvell/mwifiex/uap_txrx.c
+++ b/drivers/net/wireless/marvell/mwifiex/uap_txrx.c
@@ -475,8 +475,8 @@  void *mwifiex_process_uap_txpd(struct mwifiex_private *priv,
 
 	pkt_type = mwifiex_is_skb_mgmt_frame(skb) ? PKT_TYPE_MGMT : 0;
 
-	pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &
-			(MWIFIEX_DMA_ALIGN_SZ - 1);
+	pad = ((uintptr_t)skb->data - (sizeof(*txpd) + hroom)) &
+	       (MWIFIEX_DMA_ALIGN_SZ - 1);
 
 	skb_push(skb, sizeof(*txpd) + pad);