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ovpn: zero-initialize sockaddr before learning a floated endpoint

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ovpn_peer_endpoints_update() builds the new remote endpoint in an
on-stack struct sockaddr_storage that is left uninitialized. For IPv4
only sin_family/sin_addr/sin_port are written, leaving the 8-byte
sin_zero padding as stack garbage (for IPv6, sin6_flowinfo is left
uninitialized likewise).

ovpn_peer_reset_sockaddr() -> ovpn_bind_from_sockaddr() then memcpy()s
sizeof(struct sockaddr_in)/sizeof(struct sockaddr_in6) bytes - padding
included - into bind->remote. That buffer is later hashed with jhash()
over the same length to place the peer in the by_transp_addr table, so
the garbage padding lands the floated peer in an essentially random
bucket. Lockless lookups in ovpn_peer_get_by_transp_addr() build their
key from a zero-initialized sockaddr_storage, compute a different bucket
and fail to find the peer.

This is also a plain use of uninitialized stack memory in jhash().

Build the floated endpoint with a designated initializer so the
padding (sin_zero for IPv4, sin6_flowinfo for IPv6) is zeroed as part
of the assignment. This keeps the padding out of the by_transp_addr
hash key without memset-ing the whole sockaddr_storage on every
received packet.

Fixes: f0281c1d37 ("ovpn: add support for updating local or remote UDP endpoint")
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
This commit is contained in:
Antonio Quartulli
2026-07-28 13:48:51 +02:00
parent 59aed1eb60
commit 3f012bdbab
1 changed files with 23 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
drivers/net/ovpn/peer.c
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@@ -222,9 +222,16 @@ void ovpn_peer_endpoints_update(struct ovpn_peer *peer, struct sk_buff *skb)
*/
local_ip = &ip_hdr(skb)->daddr;
sa = (struct sockaddr_in *)&ss;
sa->sin_family = AF_INET;
sa->sin_addr.s_addr = ip_hdr(skb)->saddr;
sa->sin_port = udp_hdr(skb)->source;
/* use a designated initializer so the sin_zero padding
* is zeroed (it ends up in the by_transp_addr hash key)
* without memset-ing the whole sockaddr_storage on the
* RX fast path
*/
*sa = (struct sockaddr_in) {
.sin_family = AF_INET,
.sin_addr.s_addr = ip_hdr(skb)->saddr,
.sin_port = udp_hdr(skb)->source,
};
salen = sizeof(*sa);
reset_cache = true;
break;
@@ -250,11 +257,19 @@ void ovpn_peer_endpoints_update(struct ovpn_peer *peer, struct sk_buff *skb)
*/
local_ip = &ipv6_hdr(skb)->daddr;
sa6 = (struct sockaddr_in6 *)&ss;
sa6->sin6_family = AF_INET6;
sa6->sin6_addr = ipv6_hdr(skb)->saddr;
sa6->sin6_port = udp_hdr(skb)->source;
sa6->sin6_scope_id = ipv6_iface_scope_id(&ipv6_hdr(skb)->saddr,
skb->skb_iif);
/* use a designated initializer so the sin6_flowinfo
* padding is zeroed (it ends up in the by_transp_addr
* hash key) without memset-ing the whole
* sockaddr_storage on the RX fast path
*/
*sa6 = (struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_addr = ipv6_hdr(skb)->saddr,
.sin6_port = udp_hdr(skb)->source,
.sin6_scope_id =
ipv6_iface_scope_id(&ipv6_hdr(skb)->saddr,
skb->skb_iif),
};
salen = sizeof(*sa6);
reset_cache = true;
break;