@@ -144,7 +144,7 @@ struct hci_dev_req {
struct hci_dev_list_req {
__u16 dev_num;
- struct hci_dev_req dev_req[]; /* hci_dev_req structures */
+ struct hci_dev_req dev_req[] __counted_by(dev_num);
};
struct hci_conn_list_req {
@@ -837,7 +837,7 @@ int hci_get_dev_list(void __user *arg)
struct hci_dev *hdev;
struct hci_dev_list_req *dl;
struct hci_dev_req *dr;
- int n = 0, size, err;
+ int n = 0, err;
__u16 dev_num;
if (get_user(dev_num, (__u16 __user *) arg))
@@ -846,12 +846,11 @@ int hci_get_dev_list(void __user *arg)
if (!dev_num || dev_num > (PAGE_SIZE * 2) / sizeof(*dr))
return -EINVAL;
- size = sizeof(*dl) + dev_num * sizeof(*dr);
-
- dl = kzalloc(size, GFP_KERNEL);
+ dl = kzalloc(struct_size(dl, dev_req, dev_num), GFP_KERNEL);
if (!dl)
return -ENOMEM;
+ dl->dev_num = dev_num;
dr = dl->dev_req;
read_lock(&hci_dev_list_lock);
@@ -865,8 +864,8 @@ int hci_get_dev_list(void __user *arg)
if (hci_dev_test_flag(hdev, HCI_AUTO_OFF))
flags &= ~BIT(HCI_UP);
- (dr + n)->dev_id = hdev->id;
- (dr + n)->dev_opt = flags;
+ dr[n].dev_id = hdev->id;
+ dr[n].dev_opt = flags;
if (++n >= dev_num)
break;
@@ -874,9 +873,7 @@ int hci_get_dev_list(void __user *arg)
read_unlock(&hci_dev_list_lock);
dl->dev_num = n;
- size = sizeof(*dl) + n * sizeof(*dr);
-
- err = copy_to_user(arg, dl, size);
+ err = copy_to_user(arg, dl, struct_size(dl, dev_req, n));
kfree(dl);
return err ? -EFAULT : 0;
This is an effort to get rid of all multiplications from allocation functions in order to prevent integer overflows [1][2]. As the "dl" variable is a pointer to "struct hci_dev_list_req" and this structure ends in a flexible array: struct hci_dev_list_req { [...] struct hci_dev_req dev_req[]; /* hci_dev_req structures */ }; the preferred way in the kernel is to use the struct_size() helper to do the arithmetic instead of the calculation "size + count * size" in the kzalloc() and copy_to_user() functions. At the same time, prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). In this case, it is important to note that the logic needs a little refactoring to ensure that the "dev_num" member is initialized before the first access to the flex array. Specifically, add the assignment before the list_for_each_entry() loop. Also remove the "size" variable as it is no longer needed and refactor the list_for_each_entry() loop to use dr[n] instead of (dr + n). This way, the code is more readable, idiomatic and safer. This code was detected with the help of Coccinelle, and audited and modified manually. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1] Link: https://github.com/KSPP/linux/issues/160 [2] Signed-off-by: Erick Archer <erick.archer@outlook.com> --- include/net/bluetooth/hci_sock.h | 2 +- net/bluetooth/hci_core.c | 15 ++++++--------- 2 files changed, 7 insertions(+), 10 deletions(-)