From: Kees Cook Date: Mon, 21 Jun 2021 22:21:12 +0000 (-0700) Subject: hv_netvsc: Avoid field-overflowing memcpy() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f2fcffe392c1fd8324f131bf33d7d350eff44bb6;p=linux.git hv_netvsc: Avoid field-overflowing memcpy() In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally writing across neighboring fields. Add flexible array to represent start of buf_info, improving readability and avoid future warning where memcpy() thinks it is writing past the end of the structure. Signed-off-by: Kees Cook Signed-off-by: David S. Miller --- diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h index 442c520ab8f30..9e5eee44f7d30 100644 --- a/drivers/net/hyperv/hyperv_net.h +++ b/drivers/net/hyperv/hyperv_net.h @@ -1163,6 +1163,7 @@ struct rndis_set_request { u32 info_buflen; u32 info_buf_offset; u32 dev_vc_handle; + u8 info_buf[]; }; /* Response to NdisSetRequest */ diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c index c0e89e107d575..033ed6ed78c54 100644 --- a/drivers/net/hyperv/rndis_filter.c +++ b/drivers/net/hyperv/rndis_filter.c @@ -1051,10 +1051,8 @@ static int rndis_filter_set_packet_filter(struct rndis_device *dev, set = &request->request_msg.msg.set_req; set->oid = RNDIS_OID_GEN_CURRENT_PACKET_FILTER; set->info_buflen = sizeof(u32); - set->info_buf_offset = sizeof(struct rndis_set_request); - - memcpy((void *)(unsigned long)set + sizeof(struct rndis_set_request), - &new_filter, sizeof(u32)); + set->info_buf_offset = offsetof(typeof(*set), info_buf); + memcpy(set->info_buf, &new_filter, sizeof(u32)); ret = rndis_filter_send_request(dev, request); if (ret == 0) {