Commit 13114dc5 authored by Sabrina Dubroca's avatar Sabrina Dubroca Committed by Jakub Kicinski
Browse files

tls: fix use-after-free on failed backlog decryption 



When the decrypt request goes to the backlog and crypto_aead_decrypt
returns -EBUSY, tls_do_decryption will wait until all async
decryptions have completed. If one of them fails, tls_do_decryption
will return -EBADMSG and tls_decrypt_sg jumps to the error path,
releasing all the pages. But the pages have been passed to the async
callback, and have already been released by tls_decrypt_done.

The only true async case is when crypto_aead_decrypt returns
 -EINPROGRESS. With -EBUSY, we already waited so we can tell
tls_sw_recvmsg that the data is available for immediate copy, but we
need to notify tls_decrypt_sg (via the new ->async_done flag) that the
memory has already been released.

Fixes: 85905414 ("net: tls: handle backlogging of crypto requests")
Signed-off-by: default avatarSabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/4755dd8d9bebdefaa19ce1439b833d6199d4364c.1709132643.git.sd@queasysnail.net


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 41532b78

net/tls/tls_sw.c

+17 −7
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ struct tls_decrypt_arg { 
	struct_group(inargs,

	bool zc;

	bool async;

	bool async_done;

	u8 tail;

	);
@@ -286,15 +287,18 @@ static int tls_do_decryption(struct sock *sk, 
	}



	ret = crypto_aead_decrypt(aead_req);

	if (ret == -EINPROGRESS)

		return 0;



	if (ret == -EBUSY) {

		ret = tls_decrypt_async_wait(ctx);

		ret = ret ?: -EINPROGRESS;

		darg->async_done = true;

		/* all completions have run, we're not doing async anymore */

		darg->async = false;

		return ret;

	}

	if (ret == -EINPROGRESS) {

		return 0;

	} else if (darg->async) {



	atomic_dec(&ctx->decrypt_pending);

	}

	darg->async = false;



	return ret;
@@ -1593,8 +1597,11 @@ static int tls_decrypt_sg(struct sock *sk, struct iov_iter *out_iov, 
	/* Prepare and submit AEAD request */

	err = tls_do_decryption(sk, sgin, sgout, dctx->iv,

				data_len + prot->tail_size, aead_req, darg);

	if (err)

	if (err) {

		if (darg->async_done)

			goto exit_free_skb;

		goto exit_free_pages;

	}



	darg->skb = clear_skb ?: tls_strp_msg(ctx);

	clear_skb = NULL;
@@ -1606,6 +1613,9 @@ static int tls_decrypt_sg(struct sock *sk, struct iov_iter *out_iov, 
		return err;

	}



	if (unlikely(darg->async_done))

		return 0;



	if (prot->tail_size)

		darg->tail = dctx->tail;