A warning is triggered when the response message len exceeds
the size of rndis_message. Inside the rndis_request structure
these fields are however followed by a RNDIS_EXT_LEN padding
so it is safe to use unsafe_memcpy.
memcpy: detected field-spanning write (size 168) of single field "(void *)&request->response_msg + (sizeof(struct rndis_message) - sizeof(union rndis_message_container)) + sizeof(*req_id)" at drivers/net/hyperv/rndis_filter.c:338 (size 40)
RSP: 0018:ffffc90000144de0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8881766b4000 RCX: 0000000000000000
RDX: 0000000000000102 RSI: 0000000000009ffb RDI: 00000000ffffffff
RBP: ffffc90000144e38 R08: 0000000000000000 R09: 00000000ffffdfff
R10: ffffc90000144c48 R11: ffffffff82f56ac8 R12: ffff8881766b403c
R13: 00000000000000a8 R14: ffff888100b75000 R15: ffff888179301d00
FS: 0000000000000000(0000) GS:ffff8884d6280000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f8b024c418 CR3: 0000000176548001 CR4: 00000000003706e0
Call Trace:
<IRQ>
? _raw_spin_unlock_irqrestore+0x27/0x50
netvsc_poll+0x556/0x940 [hv_netvsc]
__napi_poll+0x2e/0x170
net_rx_action+0x299/0x2f0
__do_softirq+0xed/0x2ef
__irq_exit_rcu+0x9f/0x110
irq_exit_rcu+0xe/0x20
sysvec_hyperv_callback+0xb0/0xd0
</IRQ>
<TASK>
asm_sysvec_hyperv_callback+0x1b/0x20
RIP: 0010:native_safe_halt+0xb/0x10
Signed-off-by: Cezar Bulinaru <cbulinaru@xxxxxxxxx>
---
drivers/net/hyperv/rndis_filter.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 11f767a20444..eea777ec2541 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -20,6 +20,7 @@
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
#include <linux/ucs2_string.h>
+#include <linux/string.h>
#include "hyperv_net.h"
#include "netvsc_trace.h"
@@ -335,9 +336,10 @@ static void rndis_filter_receive_response(struct net_device *ndev,
if (resp->msg_len <=
sizeof(struct rndis_message) + RNDIS_EXT_LEN) {
memcpy(&request->response_msg, resp, RNDIS_HEADER_SIZE + sizeof(*req_id));
- memcpy((void *)&request->response_msg + RNDIS_HEADER_SIZE + sizeof(*req_id),
+ unsafe_memcpy((void *)&request->response_msg + RNDIS_HEADER_SIZE + sizeof(*req_id),
data + RNDIS_HEADER_SIZE + sizeof(*req_id),
- resp->msg_len - RNDIS_HEADER_SIZE - sizeof(*req_id));
+ resp->msg_len - RNDIS_HEADER_SIZE - sizeof(*req_id),
+ "request->response_msg is followed by a padding of RNDIS_EXT_LEN inside rndis_request");
if (request->request_msg.ndis_msg_type ==
RNDIS_MSG_QUERY && request->request_msg.msg.
query_req.oid == RNDIS_OID_GEN_MEDIA_CONNECT_STATUS)
--
2.37.1
