CVE-2020-36787

In the Linux kernel, the following vulnerability has been resolved: media:
aspeed: fix clock handling logic Video engine uses eclk and vclk for its
clock sources and its reset control is coupled with eclk so the current
clock enabling sequence works like below. Enable eclk De-assert Video
Engine reset 10ms delay Enable vclk It introduces improper reset on the
Video Engine hardware and eventually the hardware generates unexpected DMA
memory transfers that can corrupt memory region in random and sporadic
patterns. This issue is observed very rarely on some specific AST2500 SoCs
but it causes a critical kernel panic with making a various shape of
signature so it’s extremely hard to debug. Moreover, the issue is observed
even when the video engine is not actively used because udevd turns on the
video engine hardware for a short time to make a query in every boot. To
fix this issue, this commit changes the clock handling logic to make the
reset de-assertion triggered after enabling both eclk and vclk. Also, it
adds clk_unprepare call for a case when probe fails. clk: ast2600: fix
reset settings for eclk and vclk Video engine reset setting should be
coupled with eclk to match it with the setting for previous Aspeed SoCs
which is defined in clk-aspeed.c since all Aspeed SoCs are sharing a single
video engine driver. Also, reset bit 6 is defined as ‘Video Engine’ reset
in datasheet so it should be de-asserted when eclk is enabled. This commit
fixes the setting.