diff mbox series

[net,1/2] net/tls: don't copy negative amounts of data in reencrypt

Message ID 20190426003510.28641-2-jakub.kicinski@netronome.com
State Accepted
Delegated to: David Miller
Headers show
Series net/tls: fix data copies in tls_device_reencrypt() | expand

Commit Message

Jakub Kicinski April 26, 2019, 12:35 a.m. UTC 
There is no guarantee the record starts before the skb frags.
If we don't check for this condition copy amount will get
negative, leading to reads and writes to random memory locations.
Familiar hilarity ensues.

Fixes: 4799ac81e52a ("tls: Add rx inline crypto offload")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
---
 net/tls/tls_device.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index cc0256939eb6..96357060addc 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -628,14 +628,16 @@  static int tls_device_reencrypt(struct sock *sk, struct sk_buff *skb)
 	else
 		err = 0;
 
-	copy = min_t(int, skb_pagelen(skb) - offset,
-		     rxm->full_len - TLS_CIPHER_AES_GCM_128_TAG_SIZE);
+	if (skb_pagelen(skb) > offset) {
+		copy = min_t(int, skb_pagelen(skb) - offset,
+			     rxm->full_len - TLS_CIPHER_AES_GCM_128_TAG_SIZE);
 
-	if (skb->decrypted)
-		skb_store_bits(skb, offset, buf, copy);
+		if (skb->decrypted)
+			skb_store_bits(skb, offset, buf, copy);
 
-	offset += copy;
-	buf += copy;
+		offset += copy;
+		buf += copy;
+	}
 
 	skb_walk_frags(skb, skb_iter) {
 		copy = min_t(int, skb_iter->len,