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| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-02-09 13:53:45 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-02-09 14:30:07 +0100 |
| commit | feef318c855a361a1eccd880f33e88c460eb63b4 (patch) | |
| tree | 400f5a70ab3ebe0c7a3290fdb3641d71aa19f1b9 /net/ax25/af_ax25.c | |
| parent | net: dsa: fix panic when DSA master device unbinds on shutdown (diff) | |
| download | linux-feef318c855a361a1eccd880f33e88c460eb63b4.tar.xz linux-feef318c855a361a1eccd880f33e88c460eb63b4.zip | |
ax25: fix UAF bugs of net_device caused by rebinding operation
The ax25_kill_by_device() will set s->ax25_dev = NULL and
call ax25_disconnect() to change states of ax25_cb and
sock, if we call ax25_bind() before ax25_kill_by_device().
However, if we call ax25_bind() again between the window of
ax25_kill_by_device() and ax25_dev_device_down(), the values
and states changed by ax25_kill_by_device() will be reassigned.
Finally, ax25_dev_device_down() will deallocate net_device.
If we dereference net_device in syscall functions such as
ax25_release(), ax25_sendmsg(), ax25_getsockopt(), ax25_getname()
and ax25_info_show(), a UAF bug will occur.
One of the possible race conditions is shown below:
(USE) | (FREE)
ax25_bind() |
| ax25_kill_by_device()
ax25_bind() |
ax25_connect() | ...
| ax25_dev_device_down()
| ...
| dev_put_track(dev, ...) //FREE
ax25_release() | ...
ax25_send_control() |
alloc_skb() //USE |
the corresponding fail log is shown below:
===============================================================
BUG: KASAN: use-after-free in ax25_send_control+0x43/0x210
...
Call Trace:
...
ax25_send_control+0x43/0x210
ax25_release+0x2db/0x3b0
__sock_release+0x6d/0x120
sock_close+0xf/0x20
__fput+0x11f/0x420
...
Allocated by task 1283:
...
__kasan_kmalloc+0x81/0xa0
alloc_netdev_mqs+0x5a/0x680
mkiss_open+0x6c/0x380
tty_ldisc_open+0x55/0x90
...
Freed by task 1969:
...
kfree+0xa3/0x2c0
device_release+0x54/0xe0
kobject_put+0xa5/0x120
tty_ldisc_kill+0x3e/0x80
...
In order to fix these UAF bugs caused by rebinding operation,
this patch adds dev_hold_track() into ax25_bind() and
corresponding dev_put_track() into ax25_kill_by_device().
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ax25/af_ax25.c')
| -rw-r--r-- | net/ax25/af_ax25.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 3d87040d1bfc..d53cbb4e2503 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -91,6 +91,7 @@ again: spin_unlock_bh(&ax25_list_lock); lock_sock(sk); s->ax25_dev = NULL; + dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); ax25_dev_put(ax25_dev); ax25_disconnect(s, ENETUNREACH); release_sock(sk); @@ -1116,8 +1117,10 @@ static int ax25_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) } } - if (ax25_dev != NULL) + if (ax25_dev) { ax25_fillin_cb(ax25, ax25_dev); + dev_hold_track(ax25_dev->dev, &ax25_dev->dev_tracker, GFP_ATOMIC); + } done: ax25_cb_add(ax25); |