staging: gdm724x: check for buffer overflow in gdm_lte_multi_sdu_pkt()

There needs to be a check to verify that we don't read beyond the end
of "buf".  This function is called from do_rx().  The "buf" is the USB
transfer_buffer and "len" is "urb->actual_length".

Fixes: 61e121047645 ("staging: gdm7240: adding LTE USB driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YMcnl4zCwGWGDVMG@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/gdm724x/gdm_lte.c b/drivers/staging/gdm724x/gdm_lte.c
index ad9ed3df9fcfe68ec071f04435dffd594dfb83e7..d4dfaead25dac2ebfc8dd6bc50f9a652d154ff61 100644 (file)
--- a/drivers/staging/gdm724x/gdm_lte.c
+++ b/drivers/staging/gdm724x/gdm_lte.c
@@ -677,6 +677,7 @@ static void gdm_lte_multi_sdu_pkt(struct phy_dev *phy_dev, char *buf, int len)
        struct sdu *sdu = NULL;
        u8 endian = phy_dev->get_endian(phy_dev->priv_dev);
        u8 *data = (u8 *)multi_sdu->data;
+       int copied;
        u16 i = 0;
        u16 num_packet;
        u16 hci_len;
@@ -687,6 +688,12 @@ static void gdm_lte_multi_sdu_pkt(struct phy_dev *phy_dev, char *buf, int len)
        num_packet = gdm_dev16_to_cpu(endian, multi_sdu->num_packet);
 
        for (i = 0; i < num_packet; i++) {
+               copied = data - multi_sdu->data;
+               if (len < copied + sizeof(*sdu)) {
+                       pr_err("rx prevent buffer overflow");
+                       return;
+               }
+
                sdu = (struct sdu *)data;
 
                cmd_evt  = gdm_dev16_to_cpu(endian, sdu->cmd_evt);
@@ -697,7 +704,8 @@ static void gdm_lte_multi_sdu_pkt(struct phy_dev *phy_dev, char *buf, int len)
                        pr_err("rx sdu wrong hci %04x\n", cmd_evt);
                        return;
                }
-               if (hci_len < 12) {
+               if (hci_len < 12 ||
+                   len < copied + sizeof(*sdu) + (hci_len - 12)) {
                        pr_err("rx sdu invalid len %d\n", hci_len);
                        return;
                }