packet: handle too big packets for PACKET_V3
af_packet can currently overwrite kernel memory by out of bound
accesses, because it assumed a [new] block can always hold one frame.
This is not generally the case, even if most existing tools do it right.
This patch clamps too long frames as API permits, and issue a one time
error on syslog.
[ 394.357639] tpacket_rcv: packet too big, clamped from 5042 to 3966. macoff=82
In this example, packet header tp_snaplen was set to 3966,
and tp_len was set to 5042 (skb->len)
FPIIM-1253
FPIIM-1248
Change-Id: I23e3b6dfe4865fe6c4f917f773249754ba97a8dd
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.")
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed