diff options
| author | Cen Zhang (Microsoft) <blbllhy@gmail.com> | 2026-07-31 01:20:06 +0300 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-08-04 14:02:17 +0300 |
| commit | cf6f8b29befb92173659bcef6a441d274947bfae (patch) | |
| tree | 7cfdca2b076a20a411d3a7fa80da796dabf3863d /net/openvswitch | |
| parent | 1a35da325cac4d5bcad76a2aa943408a6f1d9000 (diff) | |
| download | linux-cf6f8b29befb92173659bcef6a441d274947bfae.tar.xz | |
net/openvswitch: check Ethernet header length in key_extract()
When a packet arrives on an ARPHRD_NONE device (e.g. TUN),
ovs_flow_key_extract() trusts the user-provided skb->protocol field: if
it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and
key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes
of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes
for MAC addresses and parse_ethertype() pulls 2 more, either of which
triggers a kernel BUG in __skb_pull() when the linear area is too small.
kernel BUG at include/linux/skbuff.h:2848!
RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933
ovs_flow_key_extract+0x419/0xa70
ovs_vport_receive+0x222/0x390
netdev_frame_hook+0x3e0/0x630
tun_get_user+0x2d0c/0x38e0
Fixed by calling check_header() in key_extract() before accessing the
Ethernet header.
Fixes: 217ac77a3c25 ("openvswitch: allow L3 netdev ports")
Reported-by: AutonomousCodeSecurity@microsoft.com
Reviewed-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Cen Zhang (Microsoft) <blbllhy@gmail.com>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Link: https://patch.msgid.link/20260730222006.118652-1-blbllhy@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/openvswitch')
| -rw-r--r-- | net/openvswitch/flow.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c index 66366982f604..46c1d66aad8c 100644 --- a/net/openvswitch/flow.c +++ b/net/openvswitch/flow.c @@ -889,8 +889,6 @@ static int key_extract_l3l4(struct sk_buff *skb, struct sw_flow_key *key) * Ethernet header * @key: output flow key * - * The caller must ensure that skb->len >= ETH_HLEN. - * * Initializes @skb header fields as follows: * * - skb->mac_header: the L2 header. @@ -910,8 +908,6 @@ static int key_extract_l3l4(struct sk_buff *skb, struct sw_flow_key *key) */ static int key_extract(struct sk_buff *skb, struct sw_flow_key *key) { - struct ethhdr *eth; - /* Flags are always used as part of stats */ key->tp.flags = 0; @@ -926,6 +922,13 @@ static int key_extract(struct sk_buff *skb, struct sw_flow_key *key) skb_reset_network_header(skb); key->eth.type = skb->protocol; } else { + struct ethhdr *eth; + int err; + + err = check_header(skb, ETH_HLEN); + if (unlikely(err)) + return err; + eth = eth_hdr(skb); ether_addr_copy(key->eth.src, eth->h_source); ether_addr_copy(key->eth.dst, eth->h_dest); |