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| author | Lin Ma <linma@zju.edu.cn> | 2021-12-17 10:29:41 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-12-18 12:33:56 +0000 |
| commit | 1ade48d0c27d5da1ccf4b583d8c5fc8b534a3ac8 (patch) | |
| tree | bdda352fb3d827b8c2e45cda6f3e332301017f4c /net | |
| parent | b2f37aead1b82a770c48b5d583f35ec22aabb61e (diff) | |
| download | lwn-1ade48d0c27d5da1ccf4b583d8c5fc8b534a3ac8.tar.gz lwn-1ade48d0c27d5da1ccf4b583d8c5fc8b534a3ac8.zip | |
ax25: NPD bug when detaching AX25 device
The existing cleanup routine implementation is not well synchronized
with the syscall routine. When a device is detaching, below race could
occur.
static int ax25_sendmsg(...) {
...
lock_sock()
ax25 = sk_to_ax25(sk);
if (ax25->ax25_dev == NULL) // CHECK
...
ax25_queue_xmit(skb, ax25->ax25_dev->dev); // USE
...
}
static void ax25_kill_by_device(...) {
...
if (s->ax25_dev == ax25_dev) {
s->ax25_dev = NULL;
...
}
Other syscall functions like ax25_getsockopt, ax25_getname,
ax25_info_show also suffer from similar races. To fix them, this patch
introduce lock_sock() into ax25_kill_by_device in order to guarantee
that the nullify action in cleanup routine cannot proceed when another
socket request is pending.
Signed-off-by: Hanjie Wu <nagi@zju.edu.cn>
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ax25/af_ax25.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 2f34bbdde0e8..cfca99e295b8 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -85,8 +85,10 @@ static void ax25_kill_by_device(struct net_device *dev) again: ax25_for_each(s, &ax25_list) { if (s->ax25_dev == ax25_dev) { - s->ax25_dev = NULL; spin_unlock_bh(&ax25_list_lock); + lock_sock(s->sk); + s->ax25_dev = NULL; + release_sock(s->sk); ax25_disconnect(s, ENETUNREACH); spin_lock_bh(&ax25_list_lock); |