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| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-03-28 21:00:14 +0800 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2022-03-29 10:24:34 +0200 |
| commit | 5352a761308397a0e6250fdc629bb3f615b94747 (patch) | |
| tree | e0a18ad46ffe3d7663525bb407bc8a6b892eb6ed /net | |
| parent | f19c44452b58a84d95e209b847f5495d91c9983a (diff) | |
| download | linux-5352a761308397a0e6250fdc629bb3f615b94747.tar.bz2 | |
ax25: fix UAF bug in ax25_send_control()
There are UAF bugs in ax25_send_control(), when we call ax25_release()
to deallocate ax25_dev. The possible race condition is shown below:
(Thread 1) | (Thread 2)
ax25_dev_device_up() //(1) |
| ax25_kill_by_device()
ax25_bind() //(2) |
ax25_connect() | ...
ax25->state = AX25_STATE_1 |
... | ax25_dev_device_down() //(3)
(Thread 3)
ax25_release() |
ax25_dev_put() //(4) FREE |
case AX25_STATE_1: |
ax25_send_control() |
alloc_skb() //USE |
The refcount of ax25_dev increases in position (1) and (2), and
decreases in position (3) and (4). The ax25_dev will be freed
before dereference sites in ax25_send_control().
The following is part of the report:
[ 102.297448] BUG: KASAN: use-after-free in ax25_send_control+0x33/0x210
[ 102.297448] Read of size 8 at addr ffff888009e6e408 by task ax25_close/602
[ 102.297448] Call Trace:
[ 102.303751] ax25_send_control+0x33/0x210
[ 102.303751] ax25_release+0x356/0x450
[ 102.305431] __sock_release+0x6d/0x120
[ 102.305431] sock_close+0xf/0x20
[ 102.305431] __fput+0x11f/0x420
[ 102.305431] task_work_run+0x86/0xd0
[ 102.307130] get_signal+0x1075/0x1220
[ 102.308253] arch_do_signal_or_restart+0x1df/0xc00
[ 102.308253] exit_to_user_mode_prepare+0x150/0x1e0
[ 102.308253] syscall_exit_to_user_mode+0x19/0x50
[ 102.308253] do_syscall_64+0x48/0x90
[ 102.308253] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 102.308253] RIP: 0033:0x405ae7
This patch defers the free operation of ax25_dev and net_device after
all corresponding dereference sites in ax25_release() to avoid UAF.
Fixes: 9fd75b66b8f6 ("ax25: Fix refcount leaks caused by ax25_cb_del()")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ax25/af_ax25.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 992b6e5d85d7..f5686c463bc0 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -991,10 +991,6 @@ static int ax25_release(struct socket *sock) sock_orphan(sk); ax25 = sk_to_ax25(sk); ax25_dev = ax25->ax25_dev; - if (ax25_dev) { - dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); - ax25_dev_put(ax25_dev); - } if (sk->sk_type == SOCK_SEQPACKET) { switch (ax25->state) { @@ -1056,6 +1052,10 @@ static int ax25_release(struct socket *sock) sk->sk_state_change(sk); ax25_destroy_socket(ax25); } + if (ax25_dev) { + dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); + ax25_dev_put(ax25_dev); + } sock->sk = NULL; release_sock(sk); |