Willem de Bruijn 01a658c1b9 packet: in packet_snd start writing at link layer allocation ... [ Upstream commit b84bbaf7a6 ] Packet sockets allow construction of packets shorter than dev->hard_header_len to accommodate protocols with variable length link layer headers. These packets are padded to dev->hard_header_len, because some device drivers interpret that as a minimum packet size. packet_snd reserves dev->hard_header_len bytes on allocation. SOCK_DGRAM sockets call skb_push in dev_hard_header() to ensure that link layer headers are stored in the reserved range. SOCK_RAW sockets do the same in tpacket_snd, but not in packet_snd. Syzbot was able to send a zero byte packet to a device with massive 116B link layer header, causing padding to cross over into skb_shinfo. Fix this by writing from the start of the llheader reserved range also in the case of packet_snd/SOCK_RAW. Update skb_set_network_header to the new offset. This also corrects it for SOCK_DGRAM, where it incorrectly double counted reserve due to the skb_push in dev_hard_header. Fixes: 9ed988cd59 ("packet: validate variable length ll headers") Reported-by: syzbot+71d74a5406d02057d559@syzkaller.appspotmail.com Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-05-25 16:17:24 +02:00
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af_packet.c	packet: in packet_snd start writing at link layer allocation	2018-05-25 16:17:24 +02:00
diag.c	packet: pdiag_put_ring() should return TX_RING info for TPACKET_V3	2017-01-10 21:02:42 -05:00
internal.h	packet: fix bitfield update race	2018-04-29 11:33:12 +02:00
Kconfig	packet: Diag core and basic socket info dumping	2012-08-14 16:56:33 -07:00
Makefile	packet: Diag core and basic socket info dumping	2012-08-14 16:56:33 -07:00