Subject: [PATCH 08/11] net/tls: Set count of SG entries if sk_alloc_sg returns -ENOSPC

From: Vakul Garg <[email-masked]>
Date: Thu, 6 Sep 2018 21:41:40 +0530

[ 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 <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 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 fb79caf56d0e..b81aa6d7dc45 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -170,6 +170,9 @@ static int alloc_encrypted_sg(struct sock *sk, int len)
 	rc = alloc_sg(sk, len, ctx->sg_encrypted_data,
 		      &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;
 }
 
@@ -183,6 +186,9 @@ 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;
 }
 
-- 
2.17.1