[PATCH 4.9 012/171] staging: rtl8188eu: fix possible null dereference

Greg Kroah-Hartman
2020-01-02T22:27:44Z

From: Connor Kuehl <connor.kuehl@canonical.com>

[ Upstream commit 228241944a48113470d3c3b46c88ba7fbe0a274b ]

Inside a nested 'else' block at the beginning of this function is a
call that assigns 'psta' to the return value of 'rtw_get_stainfo()'.
If 'rtw_get_stainfo()' returns NULL and the flow of control reaches
the 'else if' where 'psta' is dereferenced, then we will dereference
a NULL pointer.

Fix this by checking if 'psta' is not NULL before reading its
'psta->qos_option' data member.

Addresses-Coverity: ("Dereference null return value")

Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20190926150317.5894-1-connor.kuehl@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/staging/rtl8188eu/core/rtw_xmit.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8188eu/core/rtw_xmit.c b/drivers/staging/rtl8188eu/core/rtw_xmit.c
index 0f8b8e0bffdf..dedc313e9dea 100644
--- a/drivers/staging/rtl8188eu/core/rtw_xmit.c
+++ b/drivers/staging/rtl8188eu/core/rtw_xmit.c
@@ -805,7 +805,7 @@ s32 rtw_make_wlanhdr(struct adapter *padapter, u8 *hdr, struct pkt_attrib *pattr
memcpy(pwlanhdr->addr2, get_bssid(pmlmepriv), ETH_ALEN);
memcpy(pwlanhdr->addr3, pattrib->src, ETH_ALEN);

- if (psta->qos_option)
+ if (psta && psta->qos_option)
qos_option = true;
} else if (check_fwstate(pmlmepriv, WIFI_ADHOC_STATE) ||
check_fwstate(pmlmepriv, WIFI_ADHOC_MASTER_STATE)) {
@@ -813,7 +813,7 @@ s32 rtw_make_wlanhdr(struct adapter *padapter, u8 *hdr, struct pkt_attrib *pattr
memcpy(pwlanhdr->addr2, pattrib->src, ETH_ALEN);
memcpy(pwlanhdr->addr3, get_bssid(pmlmepriv), ETH_ALEN);

- if (psta->qos_option)
+ if (psta && psta->qos_option)
qos_option = true;
} else {
RT_TRACE(_module_rtl871x_xmit_c_, _drv_err_, ("fw_state:%x is not allowed to xmit frame\n", get_fwstate(pmlmepriv)));
--
2.20.1