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); }