The recv_buf buffers are allocated in netvsc_device_add(). Later in
netvsc_init_buf() the response to NVSP_MSG1_TYPE_SEND_RECV_BUF allows
the host to set up a recv_section_size that could be bigger than the
(default) value used for that allocation. The host-controlled value
could be used by a malicious host to bypass the check on the packet's
length in netvsc_receive() and hence to overflow the recv_buf buffer.
Move the allocation of the recv_buf buffers into netvsc_init_but().
Reported-by: Juan Vazquez <juvazq@xxxxxxxxxxxxx>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Fixes: 0ba35fe91ce34f ("hv_netvsc: Copy packets sent by Hyper-V out of the receive buffer")
---
drivers/net/hyperv/netvsc.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 0fba8257fc119..9db1ea3affbb3 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -311,7 +311,7 @@ static int netvsc_init_buf(struct hv_device *device,
struct nvsp_message *init_packet;
unsigned int buf_size;
size_t map_words;
- int ret = 0;
+ int i, ret = 0;
/* Get receive buffer area. */
buf_size = device_info->recv_sections * device_info->recv_section_size;
@@ -405,6 +405,16 @@ static int netvsc_init_buf(struct hv_device *device,
goto cleanup;
}
+ for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
+ struct netvsc_channel *nvchan = &net_device->chan_table[i];
+
+ nvchan->recv_buf = kzalloc(net_device->recv_section_size, GFP_KERNEL);
+ if (nvchan->recv_buf == NULL) {
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+ }
+
/* Setup receive completion ring.
* Add 1 to the recv_section_cnt because at least one entry in a
* ring buffer has to be empty.
@@ -1549,12 +1559,6 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
struct netvsc_channel *nvchan = &net_device->chan_table[i];
- nvchan->recv_buf = kzalloc(device_info->recv_section_size, GFP_KERNEL);
- if (nvchan->recv_buf == NULL) {
- ret = -ENOMEM;
- goto cleanup2;
- }
-
nvchan->channel = device->channel;
nvchan->net_device = net_device;
u64_stats_init(&nvchan->tx_stats.syncp);
--
2.25.1
