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staging: r8188eu: clean up NULL check for rcu pointer

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Clean up the NULL check for padapter->pnetdev->rx_handler_data.

The current code calls rcu_dereference while it holds the rcu read lock
and checks the pointer after releasing the lock. An rcu pointer may only be
used between calls to rcu_read_lock and rcu_read_unlock.

Replace the check with rcu_access_pointer. My understanding is that this
function returns the value of the pointer and needs no locking. We can
then check the pointer but we must not dereference it.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20230131090057.241779-1-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martin Kaiser
2023-01-31 10:00:57 +01:00
committed by Greg Kroah-Hartman
parent 7f0c12449a
commit c6dd307144
1 changed files with 2 additions and 6 deletions
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8
drivers/staging/r8188eu/core/rtw_xmit.c
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@@ -1631,18 +1631,14 @@ s32 rtw_xmit(struct adapter *padapter, struct sk_buff **ppkt)
struct xmit_priv *pxmitpriv = &padapter->xmitpriv;
struct xmit_frame *pxmitframe = NULL;
struct mlme_priv *pmlmepriv = &padapter->mlmepriv;
void *br_port = NULL;
s32 res;
pxmitframe = rtw_alloc_xmitframe(pxmitpriv);
if (!pxmitframe)
return -1;
rcu_read_lock();
br_port = rcu_dereference(padapter->pnetdev->rx_handler_data);
rcu_read_unlock();
if (br_port && check_fwstate(pmlmepriv, WIFI_STATION_STATE | WIFI_ADHOC_STATE)) {
if (rcu_access_pointer(padapter->pnetdev->rx_handler_data) &&
check_fwstate(pmlmepriv, WIFI_STATION_STATE | WIFI_ADHOC_STATE)) {
res = rtw_br_client_tx(padapter, ppkt);
if (res == -1) {
rtw_free_xmitframe(pxmitpriv, pxmitframe);