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Subject[PATCH net] ax25: use after free in ax25_connect
Date
sk_to_ax25(sk) needs to be called after lock_sock(sk) to avoid UAF
caused by a race condition.

Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
---
net/ax25/af_ax25.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index cfca99e295b8..c5d62420a2a8 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1127,7 +1127,7 @@ static int __must_check ax25_connect(struct socket *sock,
struct sockaddr *uaddr, int addr_len, int flags)
{
struct sock *sk = sock->sk;
- ax25_cb *ax25 = sk_to_ax25(sk), *ax25t;
+ ax25_cb *ax25, *ax25t;
struct full_sockaddr_ax25 *fsa = (struct full_sockaddr_ax25 *)uaddr;
ax25_digi *digi = NULL;
int ct = 0, err = 0;
@@ -1155,6 +1155,8 @@ static int __must_check ax25_connect(struct socket *sock,

lock_sock(sk);

+ ax25 = sk_to_ax25(sk);
+
/* deal with restarts */
if (sock->state == SS_CONNECTING) {
switch (sk->sk_state) {
--
2.25.1
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