[PATCH net-next, net v2] net/tls: Set count of SG entries if sk_alloc_sg returns -ENOSPC

[PATCH net-next, net v2] net/tls: Set count of SG entries if sk_alloc_sg returns -ENOSPC

[Vakul Garg]

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>
---
Changes since v1:
	- Added 'Fixes:' tag.
	- Marking that patch applies to both 'net-next' & 'net' branches
	- Resending after correcting system time.
	- No code changes as such

 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

Re: [PATCH net-next, net v2] net/tls: Set count of SG entries if sk_alloc_sg returns -ENOSPC

[David Miller]

From: Vakul Garg <vakul.garg@nxp.com>
Date: Thu,  6 Sep 2018 21:41:40 +0530

> 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>

Applied to 'net' and queued up for -stable.