netdev - [PATCH net-next v1] net/tls: Set count of SG entries if sk_alloc

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Date:   Wed,  5 Sep 2018 21:57:43 +0530
From:   Vakul Garg <vakul.garg@....com>
To:     netdev@...r.kernel.org
Cc:     borisp@...lanox.com, aviadye@...lanox.com, davejwatson@...com,
        davem@...emloft.net, doronrk@...com,
        Vakul Garg <vakul.garg@....com>
Subject: [PATCH net-next v1] net/tls: Set count of SG entries if sk_alloc_sg returns -ENOSPC

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.

Signed-off-by: Vakul Garg <vakul.garg@....com>
---
 net/tls/tls_sw.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index be4f2e990f9f..2dad3dc7be60 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -263,6 +263,9 @@ static int alloc_encrypted_sg(struct sock *sk, int len)
 			 &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;
 }
 
@@ -276,6 +279,9 @@ static int alloc_plaintext_sg(struct sock *sk, int len)
 			 &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;
 }
 
-- 
2.13.6