tree a14ebcccda796616efe9cc5285b817d9c405d756
parent 144677d41bf513af64e934fba61bf3220cbe8d5a
author Philippe Mathieu-Daudé <f4bug@amsat.org> 1607609770 +0100
committer Peter Maydell <peter.maydell@linaro.org> 1608039405 +0000

hw/misc/zynq_slcr: Avoid #DIV/0! error

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>