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

[Huawei PSIRT <psirt@huawei.com>]

Dear,

Thank you very much for your support. And will you assign a CVE-ID for the
issue?

Best regards,
Huawei PSIRT

-----邮件原件-----
发件人: P J P [mailto:ppandit@redhat.com] 
发送时间: 2016年10月12日 0:28
收件人: Qemu Developers
抄送: Michael S. Tsirkin; Paolo Bonzini; Huawei PSIRT; Prasad J Pandit
主题: [PATCH] char: serial: check divider value against baud base

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