From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hangyu Hua Subject: [PATCH net] ax25: use after free in ax25_connect Date: Tue, 11 Jan 2022 12:20:48 +0800 Message-ID: <20220111042048.43532-1-hbh25y@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=UvMY/BpPHYLYCpXHLFkn3wGD0r030IMs3mS/Z9JjkxE=; b=B4huMDPf/I5XDFsWvuSzqemyC/KmP1kbRmHZg++C6oVqbp5JbmVAzQgwpvPHI2R75a eFndp8C17Wl5PflRaDCVZxWcEbqa5+6UBaNvURPDfheA6K3ribm3QBuU6IOQsF33gvfv CjqRwLCo8SxPYN+3PU9wnp1g8XQZT7e3InZz01HdorpXlY2u1ZmABwxOTI3afAnpZwat i9vhYGqNVJ8YqfUT5BX0bjwabLXthH/pG1n69kGxdrzJ/ttwuvaMK9HnkU1t1NJ+JTqA QeE/kZSdavrTfUBIMdC4YD/raQ0rjw+M3FbXDOLoz/5nwzR2M6KdOEqNP0tSb1lZ4ktK ruYA== List-ID: Content-Type: text/plain; charset="us-ascii" To: jreuter@yaina.de, ralf@linux-mips.org, davem@davemloft.net, kuba@kernel.org Cc: linux-hams@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Hangyu Hua 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 --- 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