[PATCH] net: tls: fix possible race condition between do_tls_getsockopt_conf() and do_tls_setsockopt_conf()

[Hangyu Hua <hbh25y@gmail.com>]

ctx->crypto_send.info is not protected by lock_sock in
do_tls_getsockopt_conf(). A race condition between do_tls_getsockopt_conf()
and do_tls_setsockopt_conf() can cause a NULL point dereference or
use-after-free read when memcpy.

Fixes: 3c4d7559159b ("tls: kernel TLS support")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
---
 net/tls/tls_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 3735cb00905d..4956f5149b8e 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -374,6 +374,7 @@ static int do_tls_getsockopt_conf(struct sock *sk, char __user *optval,
 	}
 
 	/* get user crypto info */
+	lock_sock(sk);
 	if (tx) {
 		crypto_info = &ctx->crypto_send.info;
 		cctx = &ctx->tx;
@@ -381,6 +382,7 @@ static int do_tls_getsockopt_conf(struct sock *sk, char __user *optval,
 		crypto_info = &ctx->crypto_recv.info;
 		cctx = &ctx->rx;
 	}
+	release_sock(sk);
 
 	if (!TLS_CRYPTO_INFO_READY(crypto_info)) {
 		rc = -EBUSY;
-- 
2.34.1