[PATCH] staging: r8188eu: change the allocation type of pdata_attr

[PATCH] staging: r8188eu: change the allocation type of pdata_attr

[xkernel.wang]

From: Xiaoke Wang <xkernel.wang@foxmail.com>

`pdata_attr` was allocated by kzalloc() in go_add_group_info_attr(), but
there is a lack of error handlers along the call chain it lies and the
lifetime of `pdata_attr` is only in go_add_group_info_attr().
Therefore, changing it to a local variable on stack like the other
functions in rtw_p2p.c is a possible choice, such as
`u8 p2pie[MAX_P2P_IE_LEN] = { 0x00 };` in build_probe_resp_p2p_ie()
which is the caller of go_add_group_info_attr().

Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
---
 drivers/staging/r8188eu/core/rtw_p2p.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_p2p.c b/drivers/staging/r8188eu/core/rtw_p2p.c
index e2b6cf2..f1a5df8 100644
--- a/drivers/staging/r8188eu/core/rtw_p2p.c
+++ b/drivers/staging/r8188eu/core/rtw_p2p.c
@@ -27,15 +27,14 @@ static u32 go_add_group_info_attr(struct wifidirect_info *pwdinfo, u8 *pbuf)
 	struct list_head *phead, *plist;
 	u32 len = 0;
 	u16 attr_len = 0;
-	u8 tmplen, *pdata_attr, *pstart, *pcur;
+	u8 pdata_attr[MAX_P2P_IE_LEN] = { 0x00 };
+	u8 tmplen, *pstart, *pcur;
 	struct sta_info *psta = NULL;
 	struct adapter *padapter = pwdinfo->padapter;
 	struct sta_priv *pstapriv = &padapter->stapriv;
 
 	DBG_88E("%s\n", __func__);
 
-	pdata_attr = kzalloc(MAX_P2P_IE_LEN, GFP_KERNEL);
-
 	pstart = pdata_attr;
 	pcur = pdata_attr;
 
@@ -106,7 +105,6 @@ static u32 go_add_group_info_attr(struct wifidirect_info *pwdinfo, u8 *pbuf)
 	if (attr_len > 0)
 		len = rtw_set_p2p_attr_content(pbuf, P2P_ATTR_GROUP_INFO, attr_len, pdata_attr);
 
-	kfree(pdata_attr);
 	return len;
 }
 
-- 

Re: [PATCH] staging: r8188eu: change the allocation type of pdata_attr

[Greg KH]

On Thu, Mar 31, 2022 at 03:37:00PM +0800, xkernel.wang@foxmail.com wrote:
> From: Xiaoke Wang <xkernel.wang@foxmail.com>
> 
> `pdata_attr` was allocated by kzalloc() in go_add_group_info_attr(), but
> there is a lack of error handlers along the call chain it lies and the
> lifetime of `pdata_attr` is only in go_add_group_info_attr().
> Therefore, changing it to a local variable on stack like the other
> functions in rtw_p2p.c is a possible choice, such as
> `u8 p2pie[MAX_P2P_IE_LEN] = { 0x00 };` in build_probe_resp_p2p_ie()
> which is the caller of go_add_group_info_attr().
> 
> Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
> ---
>  drivers/staging/r8188eu/core/rtw_p2p.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/r8188eu/core/rtw_p2p.c b/drivers/staging/r8188eu/core/rtw_p2p.c
> index e2b6cf2..f1a5df8 100644
> --- a/drivers/staging/r8188eu/core/rtw_p2p.c
> +++ b/drivers/staging/r8188eu/core/rtw_p2p.c
> @@ -27,15 +27,14 @@ static u32 go_add_group_info_attr(struct wifidirect_info *pwdinfo, u8 *pbuf)
>  	struct list_head *phead, *plist;
>  	u32 len = 0;
>  	u16 attr_len = 0;
> -	u8 tmplen, *pdata_attr, *pstart, *pcur;
> +	u8 pdata_attr[MAX_P2P_IE_LEN] = { 0x00 };

As I said before, this is way too big to put on the stack.