From f7f4d4b85b83d0296dcf805b61f64c50833f5f5a Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 25 Apr 2019 17:35:09 -0700 Subject: [PATCH] net/tls: don't copy negative amounts of data in reencrypt [ Upstream commit 97e1caa517e22d62a283b876fb8aa5f4672c83dd ] 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 Reviewed-by: John Hurley Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/tls/tls_device.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c index 5f1d937c4be95..4068101d43ea7 100644 --- a/net/tls/tls_device.c +++ b/net/tls/tls_device.c @@ -610,14 +610,16 @@ 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,