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[v2] char: serial: check divider value against baud base

Message ID 1476251888-20238-1-git-send-email-ppandit@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Prasad Pandit Oct. 12, 2016, 5:58 a.m. UTC 
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 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Update per
  -> https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg02400.html

Comments

Paolo Bonzini Oct. 12, 2016, 8:13 a.m. UTC | #1 
On 12/10/2016 07:58, P J P wrote:
> 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 | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> Update per
>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg02400.html
> 
> diff --git a/hw/char/serial.c b/hw/char/serial.c
> index 3442f47..eec72b7 100644
> --- a/hw/char/serial.c
> +++ b/hw/char/serial.c
> @@ -153,8 +153,9 @@ 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. */
>      frame_size = 1;
> 

Queued, thanks.

Paolo
diff mbox

Patch

diff --git a/hw/char/serial.c b/hw/char/serial.c
index 3442f47..eec72b7 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -153,8 +153,9 @@  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. */
     frame_size = 1;