tty: n_gsm: improper skb_pull() use was leaking framed data

gsm_dlci_data_output_framed() was doing:
memcpy(dp, skb_pull(dlci->skb, len), len);

The problem is skb_pull() returns the post-increment data ptr
so the first chunk of dlci->skb->data is leaked.

Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 7290394..19b4ae0 100644 (file)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -875,7 +875,8 @@ static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
                *dp++ = last << 7 | first << 6 | 1;     /* EA */
                len--;
        }
-       memcpy(dp, skb_pull(dlci->skb, len), len);
+       memcpy(dp, dlci->skb->data, len);
+       skb_pull(dlci->skb, len);
        __gsm_data_queue(dlci, msg);
        if (last)
                dlci->skb = NULL;