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net/tls: Only attach to sockets in ESTABLISHED state 

Calling accept on a TCP socket with a TLS ulp attached results
in two sockets that share the same ulp context.
The ulp context is freed while a socket is destroyed, so
after one of the sockets is released, the second second will
trigger a use after free when it tries to access the ulp context
attached to it.
We restrict the TLS ulp to sockets in ESTABLISHED state
to prevent the scenario above.

Fixes: 3c4d755915 ("tls: kernel TLS support")
Reported-by: syzbot+904e7cd6c5c741609228@syzkaller.appspotmail.com
Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
zero-colors
Ilya Lesokhin 2018-01-16 15:31:52 +02:00 committed by David S. Miller
parent f8b39039cb
commit d91c3e17f7
1 changed files with 9 additions and 0 deletions
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9
net/tls/tls_main.c
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@ -454,6 +454,15 @@ static int tls_init(struct sock *sk)
struct tls_context *ctx;
int rc = 0;
/* The TLS ulp is currently supported only for TCP sockets
* in ESTABLISHED state.
* Supporting sockets in LISTEN state will require us
* to modify the accept implementation to clone rather then
* share the ulp context.
*/
if (sk->sk_state != TCP_ESTABLISHED)
return -ENOTSUPP;
/* allocate tls context */
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx) {