[PATCH 4.4 066/101] mwifiex: Fix memory corruption in dump_station

Greg Kroah-Hartman
2020-06-19T16:50:07Z

From: Pali Rohár <pali@kernel.org>

[ Upstream commit 3aa42bae9c4d1641aeb36f1a8585cd1d506cf471 ]

The mwifiex_cfg80211_dump_station() uses static variable for iterating
over a linked list of all associated stations (when the driver is in UAP
role). This has a race condition if .dump_station is called in parallel
for multiple interfaces. This corruption can be triggered by registering
multiple SSIDs and calling, in parallel for multiple interfaces
iw dev <iface> station dump

[16750.719775] Unable to handle kernel paging request at virtual address dead000000000110
...
[16750.899173] Call trace:
[16750.901696] mwifiex_cfg80211_dump_station+0x94/0x100 [mwifiex]
[16750.907824] nl80211_dump_station+0xbc/0x278 [cfg80211]
[16750.913160] netlink_dump+0xe8/0x320
[16750.916827] netlink_recvmsg+0x1b4/0x338
[16750.920861] ____sys_recvmsg+0x7c/0x2b0
[16750.924801] ___sys_recvmsg+0x70/0x98
[16750.928564] __sys_recvmsg+0x58/0xa0
[16750.932238] __arm64_sys_recvmsg+0x28/0x30
[16750.936453] el0_svc_common.constprop.3+0x90/0x158
[16750.941378] do_el0_svc+0x74/0x90
[16750.944784] el0_sync_handler+0x12c/0x1a8
[16750.948903] el0_sync+0x114/0x140
[16750.952312] Code: f9400003 f907f423 eb02007f 54fffd60 (b9401060)
[16750.958583] ---[ end trace c8ad181c2f4b8576 ]---

This patch drops the use of the static iterator, and instead every time
the function is called iterates to the idx-th position of the
linked-list.

It would be better to convert the code not to use linked list for
associated stations storage (since the chip has a limited number of
associated stations anyway - it could just be an array). Such a change
may be proposed in the future. In the meantime this patch can backported
into stable kernels in this simple form.

Fixes: 8baca1a34d4c ("mwifiex: dump station support in uap mode")
Signed-off-by: Pali Rohár <pali@kernel.org>
Acked-by: Ganapathi Bhat <ganapathi.bhat@nxp.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200515075924.13841-1-pali@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/mwifiex/cfg80211.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/mwifiex/cfg80211.c b/drivers/net/wireless/mwifiex/cfg80211.c
index c6c2d3304dba..8b649b8e4301 100644
--- a/drivers/net/wireless/mwifiex/cfg80211.c
+++ b/drivers/net/wireless/mwifiex/cfg80211.c
@@ -1387,7 +1387,8 @@ mwifiex_cfg80211_dump_station(struct wiphy *wiphy, struct net_device *dev,
int idx, u8 *mac, struct station_info *sinfo)
{
struct mwifiex_private *priv = mwifiex_netdev_get_priv(dev);
- static struct mwifiex_sta_node *node;
+ struct mwifiex_sta_node *node;
+ int i;

if ((GET_BSS_ROLE(priv) == MWIFIEX_BSS_ROLE_STA) &&
priv->media_connected && idx == 0) {
@@ -1397,13 +1398,10 @@ mwifiex_cfg80211_dump_station(struct wiphy *wiphy, struct net_device *dev,
mwifiex_send_cmd(priv, HOST_CMD_APCMD_STA_LIST,
HostCmd_ACT_GEN_GET, 0, NULL, true);

- if (node && (&node->list == &priv->sta_list)) {
- node = NULL;
- return -ENOENT;
- }
-
- node = list_prepare_entry(node, &priv->sta_list, list);
- list_for_each_entry_continue(node, &priv->sta_list, list) {
+ i = 0;
+ list_for_each_entry(node, &priv->sta_list, list) {
+ if (i++ != idx)
+ continue;
ether_addr_copy(mac, node->mac_addr);
return mwifiex_dump_station_info(priv, node, sinfo);
}
--
2.25.1