[PATCH 4.17 176/324] tls: fix skb_to_sgvec returning unhandled error.

Greg Kroah-Hartman
2018-08-23T08:53:08Z

From: Doron Roberts-Kedes <doronrk@fb.com>

[ Upstream commit 52ee6ef36ee10dd493cf2067311e56ca8015eb8d ]

The current code does not inspect the return value of skb_to_sgvec. This
can cause a nullptr kernel panic when the malformed sgvec is passed into
the crypto request.

Checking the return value of skb_to_sgvec and skipping decryption if it
is negative fixes this problem.

Fixes: c46234ebb4d1 ("tls: RX path for ktls")
Acked-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/tls/tls_sw.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -705,6 +705,10 @@ static int decrypt_skb(struct sock *sk,
nsg = skb_to_sgvec(skb, &sgin[1],
rxm->offset + tls_ctx->rx.prepend_size,
rxm->full_len - tls_ctx->rx.prepend_size);
+ if (nsg < 0) {
+ ret = nsg;
+ goto out;
+ }

tls_make_aad(ctx->rx_aad_ciphertext,
rxm->full_len - tls_ctx->rx.overhead_size,
@@ -716,6 +720,7 @@ static int decrypt_skb(struct sock *sk,
rxm->full_len - tls_ctx->rx.overhead_size,
skb, sk->sk_allocation);

+out:
if (sgin != &sgin_arr[0])
kfree(sgin);