Repository : ssh://git@open-mesh.org/batman-adv

On branch : next

commit 52f79c4ec1ca6255ff13284bf3c628e894e25f45 Author: Sven Eckelmann sven@narfation.org Date: Mon Nov 5 21:25:27 2012 +0100

batman-adv: Use packing of 2 for all headers before an ethernet header

All packet headers in front of an ethernet header have to be completely divisible by 2 but not by 4 to make the payload after the ethernet header again 4 bytes boundary aligned.

A packing of 2 is necessary to avoid extra padding at the end of the struct caused by a structure member which is larger than two bytes. Otherwise the structure would not fulfill the previously mentioned rule to avoid the misalignment of the payload after the ethernet header. It may also lead to leakage of information when the padding it not initialized before sending.

Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Marek Lindner lindner_marek@yahoo.de

52f79c4ec1ca6255ff13284bf3c628e894e25f45 packet.h | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/packet.h b/packet.h index 55e6935..cef1b3f 100644 --- a/packet.h +++ b/packet.h @@ -173,6 +173,18 @@ struct batadv_icmp_packet_rr { uint8_t rr[BATADV_RR_LEN][ETH_ALEN]; };

+/* All packet headers in front of an ethernet header have to be completely + * divisible by 2 but not by 4 to make the payload after the ethernet + * header again 4 bytes boundary aligned. + * + * A packing of 2 is necessary to avoid extra padding at the end of the struct + * caused by a structure member which is larger than two bytes. Otherwise + * the structure would not fulfill the previously mentioned rule to avoid the + * misalignment of the payload after the ethernet header. It may also lead to + * leakage of information when the padding it not initialized before sending. + */ +#pragma pack(2) + struct batadv_unicast_packet { struct batadv_header header; uint8_t ttvn; /* destination translation table version number */ @@ -212,7 +224,9 @@ struct batadv_bcast_packet { /* "4 bytes boundary + 2 bytes" long to make the payload after the * following ethernet header again 4 bytes boundary aligned */ -} __packed; +}; + +#pragma pack()

struct batadv_vis_packet { struct batadv_header header;