serial: 8250_pci1xxxx: fix off by one in pci1xxxx_process_read_data()

These > comparisons should be >= to prevent writing one element beyond
the end of the rx_buff[] array.  The rx_buff[] buffer has RX_BUF_SIZE
elements.  Fix the buffer overflow.

Fixes: aba8290f368d ("8250: microchip: pci1xxxx: Add Burst mode reception support in uart driver for writing into FIFO")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/ZZ7vIfj7Jgh-pJn8@moroto
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
index 558c4c7f3104ead7e7fe420c2634428651c88dd2..cd258922bd780019609fee227f55d84ed3a04246 100644 (file)
--- a/drivers/tty/serial/8250/8250_pci1xxxx.c
+++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
@@ -302,7 +302,7 @@ static void pci1xxxx_process_read_data(struct uart_port *port,
         * to read, the data is received one byte at a time.
         */
        while (valid_burst_count--) {
-               if (*buff_index > (RX_BUF_SIZE - UART_BURST_SIZE))
+               if (*buff_index >= (RX_BUF_SIZE - UART_BURST_SIZE))
                        break;
                burst_buf = (u32 *)&rx_buff[*buff_index];
                *burst_buf = readl(port->membase + UART_RX_BURST_FIFO);
@@ -311,7 +311,7 @@ static void pci1xxxx_process_read_data(struct uart_port *port,
        }
 
        while (*valid_byte_count) {
-               if (*buff_index > RX_BUF_SIZE)
+               if (*buff_index >= RX_BUF_SIZE)
                        break;
                rx_buff[*buff_index] = readb(port->membase +
                                             UART_RX_BYTE_FIFO);