[Qemu-devel] [PATCH] char: serial: check divider value against baud base

[P J P <ppandit@redhat.com>]

From: Prasad J Pandit <pjp@fedoraproject.org>

16550A UART device uses an oscillator to generate frequencies
(baud base), which decide communication speed. This speed could
be changed by dividing it by a divider. If the divider is
greater than the baud base, speed is set to zero, leading to a
divide by zero error. Add check to avoid it.

Reported-by: Huawei PSIRT <psirt@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/char/serial.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/char/serial.c b/hw/char/serial.c
index 3442f47..f659bbd 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -153,7 +153,7 @@ static void serial_update_parameters(SerialState *s)
     int speed, parity, data_bits, stop_bits, frame_size;
     QEMUSerialSetParams ssp;
 
-    if (s->divider == 0)
+    if (s->divider == 0 || s->divider > s->baudbase)
         return;
 
     /* Start bit. */
-- 
2.5.5