From: Takashi Iwai
mainline inclusion
from mainline-v5.14-rc7
commit 99c23da0eed4fd20cae8243f2b51e10e66aa0951
category: bugfix
issue: #I4NRS5
CVE: CVE-2021-3640
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
-------------------------------------------------
The sco_send_frame() also takes lock_sock() during memcpy_from_msg()
call that may be endlessly blocked by a task with userfaultd
technique, and this will result in a hung task watchdog trigger.
Just like the similar fix for hci_sock_sendmsg() in commit
92c685dc5de0 ("Bluetooth: reorganize functions..."), this patch moves
the memcpy_from_msg() out of lock_sock() for addressing the hang.
This should be the last piece for fixing CVE-2021-3640 after a few
already queued fixes.
Signed-off-by: Takashi Iwai
Signed-off-by: Marcel Holtmann
Signed-off-by: Lijun Fang
Reviewed-by: Xiu Jianfeng
Reviewed-by: Jason Yan
Signed-off-by: Chen Jun
Signed-off-by: Zheng Zengkai
Signed-off-by: Yu Changchun
---
net/bluetooth/sco.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index cb2b11683082..918df8d0e8b6 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -281,7 +281,8 @@ static int sco_connect(struct hci_dev *hdev, struct sock *sk)
return err;
}
-static int sco_send_frame(struct sock *sk, struct msghdr *msg, int len)
+static int sco_send_frame(struct sock *sk, void *buf, int len,
+ unsigned int msg_flags)
{
struct sco_conn *conn = sco_pi(sk)->conn;
struct sk_buff *skb;
@@ -293,15 +294,11 @@ static int sco_send_frame(struct sock *sk, struct msghdr *msg, int len)
BT_DBG("sk %p len %d", sk, len);
- skb = bt_skb_send_alloc(sk, len, msg->msg_flags & MSG_DONTWAIT, &err);
+ skb = bt_skb_send_alloc(sk, len, msg_flags & MSG_DONTWAIT, &err);
if (!skb)
return err;
- if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
- kfree_skb(skb);
- return -EFAULT;
- }
-
+ memcpy(skb_put(skb, len), buf, len);
hci_send_sco(conn->hcon, skb);
return len;
@@ -726,6 +723,7 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg,
size_t len)
{
struct sock *sk = sock->sk;
+ void *buf;
int err;
BT_DBG("sock %p, sk %p", sock, sk);
@@ -737,14 +735,24 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg,
if (msg->msg_flags & MSG_OOB)
return -EOPNOTSUPP;
+ buf = kmalloc(len, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ if (memcpy_from_msg(buf, msg, len)) {
+ kfree(buf);
+ return -EFAULT;
+ }
+
lock_sock(sk);
if (sk->sk_state == BT_CONNECTED)
- err = sco_send_frame(sk, msg, len);
+ err = sco_send_frame(sk, buf, len, msg->msg_flags);
else
err = -ENOTCONN;
release_sock(sk);
+ kfree(buf);
return err;
}
--
2.25.1
