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xfrm_user: fix info leak in copy_to_user_tmpl()

The memory used for the template copy is a local stack variable. As
struct xfrm_user_tmpl contains multiple holes added by the compiler for
alignment, not initializing the memory will lead to leaking stack bytes
to userland. Add an explicit memset(0) to avoid the info leak.

Initial version of the patch by Brad Spengler.

Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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1 parent 7b78983 commit 1f86840f897717f86d523a13e99a447e6a5d2fa5 @minipli minipli committed with davem330 Sep 19, 2012
Showing with 1 addition and 0 deletions.
  1. +1 −0 net/xfrm/xfrm_user.c
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@@ -1425,6 +1425,7 @@ static int copy_to_user_tmpl(struct xfrm_policy *xp, struct sk_buff *skb)
struct xfrm_user_tmpl *up = &vec[i];
struct xfrm_tmpl *kp = &xp->xfrm_vec[i];
+ memset(up, 0, sizeof(*up));
memcpy(&up->id, &kp->id, sizeof(up->id));
up->family = kp->encap_family;
memcpy(&up->saddr, &kp->saddr, sizeof(up->saddr));

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