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Date: Fri, 27 May 2022 23:18:22 +0800
From: Duoming Zhou <duoming@....edu.cn>
To: linux-hams@...r.kernel.org
Cc: jreuter@...na.de, ralf@...ux-mips.org, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
thomas@...erried.de, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH v2] ax25: Fix ax25 session cleanup problem in ax25_release
The timers of ax25 are used for correct session cleanup.
If we use ax25_release() to close ax25 sessions and
ax25_dev is not null, the del_timer_sync() functions in
ax25_release() will execute. As a result, the sessions
could not be cleaned up correctly, because the timers
have stopped.
This patch adds a device_up flag in ax25_dev in order to
judge whether the device is up. If there are sessions to
be cleaned up, the del_timer_sync() in ax25_release() will
not execute. What's more, we add ax25_cb_del() in
ax25_kill_by_device(), because the timers have been stopped
and there are no functions that could delete ax25_cb if we
do not call ax25_release().
Fixes: 82e31755e55f ("ax25: Fix UAF bugs in ax25 timers")
Reported-and-tested-by: Thomas Osterried <thomas@...erried.de>
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
Changes in v2:
- Add ax25_cb_del() in ax25_kill_by_device().
include/net/ax25.h | 1 +
net/ax25/af_ax25.c | 15 ++++++++++-----
net/ax25/ax25_dev.c | 1 +
3 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/include/net/ax25.h b/include/net/ax25.h
index 0f9790c455b..a427a05672e 100644
--- a/include/net/ax25.h
+++ b/include/net/ax25.h
@@ -228,6 +228,7 @@ typedef struct ax25_dev {
ax25_dama_info dama;
#endif
refcount_t refcount;
+ bool device_up;
} ax25_dev;
typedef struct ax25_cb {
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 363d47f9453..92cbb08a6c5 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -81,6 +81,7 @@ static void ax25_kill_by_device(struct net_device *dev)
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
return;
+ ax25_dev->device_up = false;
spin_lock_bh(&ax25_list_lock);
again:
@@ -91,6 +92,7 @@ static void ax25_kill_by_device(struct net_device *dev)
spin_unlock_bh(&ax25_list_lock);
ax25_disconnect(s, ENETUNREACH);
s->ax25_dev = NULL;
+ ax25_cb_del(s);
spin_lock_bh(&ax25_list_lock);
goto again;
}
@@ -104,6 +106,7 @@ static void ax25_kill_by_device(struct net_device *dev)
ax25_dev_put(ax25_dev);
}
release_sock(sk);
+ ax25_cb_del(s);
spin_lock_bh(&ax25_list_lock);
sock_put(sk);
/* The entry could have been deleted from the
@@ -1053,11 +1056,13 @@ static int ax25_release(struct socket *sock)
ax25_destroy_socket(ax25);
}
if (ax25_dev) {
- del_timer_sync(&ax25->timer);
- del_timer_sync(&ax25->t1timer);
- del_timer_sync(&ax25->t2timer);
- del_timer_sync(&ax25->t3timer);
- del_timer_sync(&ax25->idletimer);
+ if (!ax25_dev->device_up) {
+ del_timer_sync(&ax25->timer);
+ del_timer_sync(&ax25->t1timer);
+ del_timer_sync(&ax25->t2timer);
+ del_timer_sync(&ax25->t3timer);
+ del_timer_sync(&ax25->idletimer);
+ }
dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index d2a244e1c26..5451be15e07 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -62,6 +62,7 @@ void ax25_dev_device_up(struct net_device *dev)
ax25_dev->dev = dev;
dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC);
ax25_dev->forward = NULL;
+ ax25_dev->device_up = true;
ax25_dev->values[AX25_VALUES_IPDEFMODE] = AX25_DEF_IPDEFMODE;
ax25_dev->values[AX25_VALUES_AXDEFMODE] = AX25_DEF_AXDEFMODE;
--
2.17.1
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