From: Daniel Borkmann Date: Mon, 5 Aug 2013 10:49:35 +0000 (+0200) Subject: net: esp{4,6}: fix potential MTU calculation overflows X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=7921895a5e852fc99de347bc0600659997de9298;p=openwrt%2Fstaging%2Fblogic.git net: esp{4,6}: fix potential MTU calculation overflows Commit 91657eafb ("xfrm: take net hdr len into account for esp payload size calculation") introduced a possible interger overflow in esp{4,6}_get_mtu() handlers in case of x->props.mode equals XFRM_MODE_TUNNEL. Thus, the following expression will overflow unsigned int net_adj; ... net_adj = 0; ... return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - net_adj) & ~(align - 1)) + (net_adj - 2); where (net_adj - 2) would be evaluated as + (0 - 2) in an unsigned context. Fix it by simply removing brackets as those operations here do not need to have special precedence. Signed-off-by: Daniel Borkmann Cc: Benjamin Poirier Cc: Steffen Klassert Acked-by: Benjamin Poirier Signed-off-by: David S. Miller --- diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index ab3d814bc80a..109ee89f123e 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -477,7 +477,7 @@ static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) } return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - - net_adj) & ~(align - 1)) + (net_adj - 2); + net_adj) & ~(align - 1)) + net_adj - 2; } static void esp4_err(struct sk_buff *skb, u32 info) diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c index 40ffd72243a4..aeac0dc3635d 100644 --- a/net/ipv6/esp6.c +++ b/net/ipv6/esp6.c @@ -425,7 +425,7 @@ static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) net_adj = 0; return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - - net_adj) & ~(align - 1)) + (net_adj - 2); + net_adj) & ~(align - 1)) + net_adj - 2; } static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,