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Subject[PATCH] net/appletalk: fix minor pointer leak to userspace in SIOCFINDIPDDPRT
Fields ->dev and ->next of struct ipddp_route may be copied to
userspace on the SIOCFINDIPDDPRT ioctl. This is only accessible
to CAP_NET_ADMIN though. Let's manually copy the relevant fields
instead of using memcpy().

BugLink: http://blog.infosectcbr.com.au/2018/09/linux-kernel-infoleaks.html
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
drivers/net/appletalk/ipddp.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/appletalk/ipddp.c b/drivers/net/appletalk/ipddp.c
index 9375cef..3d27616 100644
--- a/drivers/net/appletalk/ipddp.c
+++ b/drivers/net/appletalk/ipddp.c
@@ -283,8 +283,12 @@ static int ipddp_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
case SIOCFINDIPDDPRT:
spin_lock_bh(&ipddp_route_lock);
rp = __ipddp_find_route(&rcp);
- if (rp)
- memcpy(&rcp2, rp, sizeof(rcp2));
+ if (rp) {
+ memset(&rcp2, 0, sizeof(rcp2));
+ rcp2.ip = rp->ip;
+ rcp2.at = rp->at;
+ rcp2.flags = rp->flags;
+ }
spin_unlock_bh(&ipddp_route_lock);

if (rp) {
--
2.8.0.rc2.1.gbe9624a
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