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

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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: 8590541473 ("net: tls: handle backlogging of crypto requests")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/4755dd8d9bebdefaa19ce1439b833d6199d4364c.1709132643.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Sabrina Dubroca 2024-02-28 23:44:00 +01:00 committed by Jakub Kicinski
parent 41532b785e
commit 13114dc554
1 changed files with 17 additions and 7 deletions
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24
net/tls/tls_sw.c
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@ -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;
}
if (ret == -EINPROGRESS) {
return 0;
} else if (darg->async) {
atomic_dec(&ctx->decrypt_pending);
darg->async_done = true;
/* all completions have run, we're not doing async anymore */
darg->async = false;
return ret;
}
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;