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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Vakul Garg <vakul.garg@nxp.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.18 007/235] net/tls: Set count of SG entries if sk_alloc_sg returns -ENOSPC
Date:   Mon, 24 Sep 2018 13:49:53 +0200
Message-Id: <20180924113105.027790477@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vakul Garg <vakul.garg@nxp.com>

[ Upstream commit 52ea992cfac357b73180d5c051dca43bc8d20c2a ]

tls_sw_sendmsg() allocates plaintext and encrypted SG entries using
function sk_alloc_sg(). In case the number of SG entries hit
MAX_SKB_FRAGS, sk_alloc_sg() returns -ENOSPC and sets the variable for
current SG index to '0'. This leads to calling of function
tls_push_record() with 'sg_encrypted_num_elem = 0' and later causes
kernel crash. To fix this, set the number of SG elements to the number
of elements in plaintext/encrypted SG arrays in case sk_alloc_sg()
returns -ENOSPC.

Fixes: 3c4d7559159b ("tls: kernel TLS support")
Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/tls/tls_sw.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -149,6 +149,9 @@ static int alloc_encrypted_sg(struct soc
 			 &ctx->sg_encrypted_num_elem,
 			 &ctx->sg_encrypted_size, 0);
 
+	if (rc == -ENOSPC)
+		ctx->sg_encrypted_num_elem = ARRAY_SIZE(ctx->sg_encrypted_data);
+
 	return rc;
 }
 
@@ -162,6 +165,9 @@ static int alloc_plaintext_sg(struct soc
 			 &ctx->sg_plaintext_num_elem, &ctx->sg_plaintext_size,
 			 tls_ctx->pending_open_record_frags);
 
+	if (rc == -ENOSPC)
+		ctx->sg_plaintext_num_elem = ARRAY_SIZE(ctx->sg_plaintext_data);
+
 	return rc;
 }