From: Daniel Starke daniel.starke@siemens.com
commit fd442e5ba30aaa75ea47b32149e7a3110dc20a46 upstream.
'len' is decreased after each octet that has its EA bit set to 0, which means that the value is encoded with additional octets. However, the final octet does not decreases 'len' which results in 'len' being one byte too long. A buffer over-read may occur in tty_insert_flip_string() as it tries to read one byte more than the passed content size of 'data'. Decrease 'len' also for the final octet which has the EA bit set to 1 to write the correct number of bytes from the internal receive buffer to the virtual tty.
Fixes: 2e124b4a390c ("TTY: switch tty_flip_buffer_push") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke daniel.starke@siemens.com Link: https://lore.kernel.org/r/20220504081733.3494-1-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/n_gsm.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1587,6 +1587,7 @@ static void gsm_dlci_data(struct gsm_dlc if (len == 0) return; } + len--; slen++; tty = tty_port_tty_get(port); if (tty) {