[PATCH 5.4 006/389] wifi: mac80211_hwsim: fix race condition in pending packet

Greg Kroah-Hartman
2022-08-23T11:11:16Z

From: Jeongik Cha <jeongik@google.com>

commit 4ee186fa7e40ae06ebbfbad77e249e3746e14114 upstream.

A pending packet uses a cookie as an unique key, but it can be duplicated
because it didn't use atomic operators.

And also, a pending packet can be null in hwsim_tx_info_frame_received_nl
due to race condition with mac80211_hwsim_stop.

For this,
* Use an atomic type and operator for a cookie
* Add a lock around the loop for pending packets

Signed-off-by: Jeongik Cha <jeongik@google.com>
Link: https://lore.kernel.org/r/20220704084354.3556326-1-jeongik@google.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/wireless/mac80211_hwsim.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -527,7 +527,7 @@ struct mac80211_hwsim_data {
bool ps_poll_pending;
struct dentry *debugfs;

- uintptr_t pending_cookie;
+ atomic64_t pending_cookie;
struct sk_buff_head pending; /* packets pending */
/*
* Only radios in the same group can communicate together (the
@@ -1044,7 +1044,7 @@ static void mac80211_hwsim_tx_frame_nl(s
int i;
struct hwsim_tx_rate tx_attempts[IEEE80211_TX_MAX_RATES];
struct hwsim_tx_rate_flag tx_attempts_flags[IEEE80211_TX_MAX_RATES];
- uintptr_t cookie;
+ u64 cookie;

if (data->ps != PS_DISABLED)
hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PM);
@@ -1113,8 +1113,7 @@ static void mac80211_hwsim_tx_frame_nl(s
goto nla_put_failure;

/* We create a cookie to identify this skb */
- data->pending_cookie++;
- cookie = data->pending_cookie;
+ cookie = (u64)atomic64_inc_return(&data->pending_cookie);
info->rate_driver_data[0] = (void *)cookie;
if (nla_put_u64_64bit(skb, HWSIM_ATTR_COOKIE, cookie, HWSIM_ATTR_PAD))
goto nla_put_failure;
@@ -3260,6 +3259,7 @@ static int hwsim_tx_info_frame_received_
const u8 *src;
unsigned int hwsim_flags;
int i;
+ unsigned long flags;
bool found = false;

if (!info->attrs[HWSIM_ATTR_ADDR_TRANSMITTER] ||
@@ -3284,18 +3284,20 @@ static int hwsim_tx_info_frame_received_
goto out;

/* look for the skb matching the cookie passed back from user */
+ spin_lock_irqsave(&data2->pending.lock, flags);
skb_queue_walk_safe(&data2->pending, skb, tmp) {
u64 skb_cookie;

txi = IEEE80211_SKB_CB(skb);
- skb_cookie = (u64)(uintptr_t)txi->rate_driver_data[0];
+ skb_cookie = (u64)txi->rate_driver_data[0];

if (skb_cookie == ret_skb_cookie) {
- skb_unlink(skb, &data2->pending);
+ __skb_unlink(skb, &data2->pending);
found = true;
break;
}
}
+ spin_unlock_irqrestore(&data2->pending.lock, flags);

/* not found */
if (!found)