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Subject[PATCH] tty: atmel_serial: fix a NULL pointer dereference
Date
In case dmaengine_prep_dma_cyclic fails, the fix return a proper
error code to avoid NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
drivers/tty/serial/atmel_serial.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 05147fe24343..cf560d05008c 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1237,8 +1237,10 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
dma_cap_set(DMA_CYCLIC, mask);

atmel_port->chan_rx = dma_request_slave_channel(mfd_dev, "rx");
- if (atmel_port->chan_rx == NULL)
+ if (atmel_port->chan_rx == NULL) {
+ ret = -EINVAL;
goto chan_err;
+ }
dev_info(port->dev, "using %s for rx DMA transfers\n",
dma_chan_name(atmel_port->chan_rx));

@@ -1257,6 +1259,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port)

if (!nent) {
dev_dbg(port->dev, "need to release resource of dma\n");
+ ret = -EINVAL;
goto chan_err;
} else {
dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
@@ -1288,6 +1291,11 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
sg_dma_len(&atmel_port->sg_rx)/2,
DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT);
+ if (!desc) {
+ dev_err(port->dev, "Preparing DMA cyclic failed\n");
+ ret = -ENOMEM;
+ goto chan_err;
+ }
desc->callback = atmel_complete_rx_dma;
desc->callback_param = port;
atmel_port->desc_rx = desc;
@@ -1300,7 +1308,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
atmel_port->use_dma_rx = 0;
if (atmel_port->chan_rx)
atmel_release_rx_dma(port);
- return -EINVAL;
+ return ret;
}

static void atmel_uart_timer_callback(struct timer_list *t)
--
2.17.1
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