| From | Greg Kroah-Hartman <> | Subject | [ 036/110] ipv6: gre: correct calculation of max_headroom | Date | Fri, 11 Oct 2013 12:38:16 -0700 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: Hannes Frederic Sowa <hannes@stressinduktion.org>
[ Upstream commit 3da812d860755925da890e8c713f2d2e2d7b1bae ]
gre_hlen already accounts for sizeof(struct ipv6_hdr) + gre header, so initialize max_headroom to zero. Otherwise the
if (encap_limit >= 0) { max_headroom += 8; mtu -= 8; }
increments an uninitialized variable before max_headroom was reset.
Found with coverity: 728539
Cc: Dmitry Kozlov <xeb@mail.ru> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv6/ip6_gre.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -620,7 +620,7 @@ static netdev_tx_t ip6gre_xmit2(struct s struct ip6_tnl *tunnel = netdev_priv(dev); struct net_device *tdev; /* Device to other host */ struct ipv6hdr *ipv6h; /* Our new IP header */ - unsigned int max_headroom; /* The extra header space needed */ + unsigned int max_headroom = 0; /* The extra header space needed */ int gre_hlen; struct ipv6_tel_txoption opt; int mtu; @@ -693,7 +693,7 @@ static netdev_tx_t ip6gre_xmit2(struct s tunnel->err_count = 0; } - max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen + dst->header_len; + max_headroom += LL_RESERVED_SPACE(tdev) + gre_hlen + dst->header_len; if (skb_headroom(skb) < max_headroom || skb_shared(skb) || (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
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