There are a number of bugs here:
1) If "count" is less than sizeof(dump_data.data) then it copies
uninitialized data.
2) If simple_write_to_buffer() returns -EFAULT then we run into a
problem "ret < count" comparison. "count" is an unsigned long so the
comparison is type promoted to unsigned long and the negative returns
become high positive values. That also results in copying
uninitialized data.
3) If "*ppos" is non-zero then the first part of the dump_data
buffer is uninitialized. Using copy_from_user() instead of
simple_write_to_buffer() is more appropriate here.
Fixes: d5d5df6da0aa ("Bluetooth: Add vhci devcoredump support")
Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>
---
>From static analysis. Untested.
drivers/bluetooth/hci_vhci.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index 691fe93b1976..40e2b9fa11a2 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -323,17 +323,21 @@ static ssize_t force_devcd_write(struct file *file, const char __user *user_buf,
struct hci_dev *hdev = data->hdev;
struct sk_buff *skb = NULL;
struct devcoredump_test_data dump_data;
+ size_t data_size;
int ret;
- ret = simple_write_to_buffer(&dump_data, sizeof(dump_data), ppos,
- user_buf, count);
- if (ret < count)
- return ret;
+ if (count < offsetof(struct devcoredump_test_data, data) ||
+ count > sizeof(dump_data))
+ return -EINVAL;
+
+ if (copy_from_user(&dump_data, user_buf, count))
+ return -EFAULT;
- skb = alloc_skb(sizeof(dump_data.data), GFP_ATOMIC);
+ data_size = count - offsetof(struct devcoredump_test_data, data);
+ skb = alloc_skb(data_size, GFP_ATOMIC);
if (!skb)
return -ENOMEM;
- skb_put_data(skb, &dump_data.data, sizeof(dump_data.data));
+ skb_put_data(skb, &dump_data.data, data_size);
hci_devcd_register(hdev, vhci_coredump, vhci_coredump_hdr, NULL);
--
2.39.1
