Malicious user can set the feedback divisor for the PLLs
to zero, triggering a floating-point exception (SIGFPE).
As the datasheet [*] is not clear how hardware behaves
when these bits are zeroes, use the maximum divisor
possible (128) to avoid the software FPE.
[*] Zynq-7000 TRM, UG585 (v1.12.2)
B.28 System Level Control Registers (slcr)
-> "Register (slcr) ARM_PLL_CTRL"
25.10.4 PLLs
-> "Software-Controlled PLL Update"
Fixes: 38867cb7ec9 ("hw/misc/zynq_slcr: add clock generation for uarts")
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Message-id: 20201210141610.884600-1-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
98a8cc741d