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[PULL,18/50] char: serial: check divider value against baud base

Message ID 1477316855-42218-19-git-send-email-pbonzini@redhat.com
State New
Headers show

Commit Message

Paolo Bonzini Oct. 24, 2016, 1:47 p.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>
Message-Id: <1476251888-20238-1-git-send-email-ppandit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/char/serial.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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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;