From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Currently, the pointer em485 is dereferenced to get p and then later
em485 is checked to see if it is null before calling __start_tx. In
the case where em485 is null, we get a null pointer dereference. Fix
this by moving the deference and the associated spinlock/unlocks on
p to the code block where em485 is known to be not null.
Detected by CoverityScan, CID#14555001 ("Dereference before null check")
Fixes 6e0a5de2136b ("serial: 8250: Use hrtimers for rs485 delays")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 4726aa276968..c20b581313f0 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1606,18 +1606,18 @@ static inline void start_tx_rs485(struct uart_port *port)
static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t)
{
struct uart_8250_em485 *em485;
- struct uart_8250_port *p;
unsigned long flags;
em485 = container_of(t, struct uart_8250_em485, start_tx_timer);
- p = em485->port;
- spin_lock_irqsave(&p->port.lock, flags);
if (em485 &&
em485->active_timer == &em485->start_tx_timer) {
+ struct uart_8250_port *p = em485->port;
+
+ spin_lock_irqsave(&p->port.lock, flags);
__start_tx(&p->port);
em485->active_timer = NULL;
+ spin_unlock_irqrestore(&p->port.lock, flags);
}
- spin_unlock_irqrestore(&p->port.lock, flags);
return HRTIMER_NORESTART;
}
--
2.14.1
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