From: Rohit Maheshwari <rohitm@chelsio.com>
Date: Mon, 9 Nov 2020 16:21:35 +0530
Subject: ch_ktls: Correction in trimmed_len calculation
Patch-mainline: v5.10-rc4
Git-commit: c68a28a9e2798a4602dde1c77046a3b577eb31f4
References: jsc#SLE-15129

trimmed length calculation goes wrong if skb has only tag part
to send. It should be zero if there is no data bytes apart from
TAG.

Fixes: dc05f3df8fac ("chcr: Handle first or middle part of record")
Signed-off-by: Rohit Maheshwari <rohitm@chelsio.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c |   11 ++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c
@@ -1729,10 +1729,13 @@ static int chcr_short_record_handler(str
 
 	if (remaining_record > 0 &&
 	    remaining_record < TLS_CIPHER_AES_GCM_128_TAG_SIZE) {
-		int trimmed_len = data_len -
-			(TLS_CIPHER_AES_GCM_128_TAG_SIZE - remaining_record);
-		/* don't process the pkt if it is only a partial tag */
-		if (data_len < TLS_CIPHER_AES_GCM_128_TAG_SIZE)
+		int trimmed_len = 0;
+
+		if (tls_end_offset > TLS_CIPHER_AES_GCM_128_TAG_SIZE)
+			trimmed_len = data_len -
+				      (TLS_CIPHER_AES_GCM_128_TAG_SIZE -
+				       remaining_record);
+		if (!trimmed_len)
 			goto out;
 
 		WARN_ON(trimmed_len > data_len);