The cadence UART attempts to avoid allowing the guset to set invalid
baud rate register values in the uart_write() function. However it
does the "mask to the size of the register field" and "check for
invalid values" in the wrong order, which means that a malicious
guest can get a bogus value into the register by setting also some
high bits in the value, and cause QEMU to crash by division-by-zero.
Do the mask before the bounds check instead of afterwards.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1493
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
hw/char/cadence_uart.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)