[PATCH v2] tty: serial: fsl_lpuart.c: prevent a bad shift operation

[B K Karthik]

prevent a bad shift operation by verifying that
the argument to fls is non zero.

Reported-by: "Vabhav Sharma (OSS)" <vabhav.sharma@xxxxxxxxxxx>
Signed-off-by: B K Karthik <bkkarthik@xxxxxxxxxxxx>
---
v1 -> v2:
	added Reported-by tag

 drivers/tty/serial/fsl_lpuart.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 7ca642249224..0cc64279cd2d 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1168,7 +1168,8 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 	 * 10ms at any baud rate.
 	 */
 	sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud /  bits / 1000) * 2;
-	sport->rx_dma_rng_buf_len = (1 << (fls(sport->rx_dma_rng_buf_len) - 1));
+	if (sport->rx_dma_rng_buf_len != 0)
+		sport->rx_dma_rng_buf_len = (1 << (fls(sport->rx_dma_rng_buf_len) - 1));
 	if (sport->rx_dma_rng_buf_len < 16)
 		sport->rx_dma_rng_buf_len = 16;
 
-- 
2.20.1

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