[SRU][F][PATCH 2/3] tls: separate no-async decryption request handling from async

[Juerg Haefliger]

From: Sabrina Dubroca <sd at queasysnail.net>

If we're not doing async, the handling is much simpler. There's no
reference counting, we just need to wait for the completion to wake us
up and return its result.

We should preferably also use a separate crypto_wait. I'm not seeing a
UAF as I did in the past, I think aec7961916f3 ("tls: fix race between
async notify and socket close") took care of it.

This will make the next fix easier.

Signed-off-by: Sabrina Dubroca <sd at queasysnail.net>
Link: https://lore.kernel.org/r/47bde5f649707610eaef9f0d679519966fc31061.1709132643.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
(cherry picked from commit 41532b785e9d79636b3815a64ddf6a096647d011)
CVE-2024-26800
Signed-off-by: Juerg Haefliger <juerg.haefliger at canonical.com>
---
 net/tls/tls_sw.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 9fade9e24911..c91a057b35a8 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -275,9 +275,15 @@ static int tls_do_decryption(struct sock *sk,
 		BUILD_BUG_ON_INVALID(atomic_read(&ctx->decrypt_pending) < 1);
 		atomic_inc(&ctx->decrypt_pending);
 	} else {
+		DECLARE_CRYPTO_WAIT(wait);
+
 		aead_request_set_callback(aead_req,
 					  CRYPTO_TFM_REQ_MAY_BACKLOG,
-					  crypto_req_done, &ctx->async_wait);
+					  crypto_req_done, &wait);
+		ret = crypto_aead_decrypt(aead_req);
+		if (ret == -EINPROGRESS || ret == -EBUSY)
+			ret = crypto_wait_req(ret, &wait);
+		return ret;
 	}
 
 	ret = crypto_aead_decrypt(aead_req);
@@ -286,10 +292,7 @@ static int tls_do_decryption(struct sock *sk,
 		ret = ret ?: -EINPROGRESS;
 	}
 	if (ret == -EINPROGRESS) {
-		if (darg->async)
-			return 0;
-
-		ret = crypto_wait_req(ret, &ctx->async_wait);
+		return 0;
 	} else if (darg->async) {
 		atomic_dec(&ctx->decrypt_pending);
 	}
-- 
2.43.0