[PATCH v2] ax25: Fix ax25 session cleanup problem in ax25_release
From: Duoming Zhou <hidden>
Date: 2022-05-27 15:20:07
Also in:
linux-hams, lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted>
Signed-off-by: Duoming Zhou <redacted>
---
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