| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2020-36787: media: aspeed: fix clock handling logic |
| |
| Description |
| =========== |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2020-36787 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.0 with commit d2b4387f3bdf016e266d23cf657465f557721488 and fixed in 5.4.119 with commit 1dc1d30ac101bb8335d9852de2107af60c2580e7 |
| Issue introduced in 5.0 with commit d2b4387f3bdf016e266d23cf657465f557721488 and fixed in 5.10.37 with commit a59d01384c80a8a4392665802df57c3df20055f5 |
| Issue introduced in 5.0 with commit d2b4387f3bdf016e266d23cf657465f557721488 and fixed in 5.11.21 with commit 2964c37563e86cfdc439f217eb3c5a69adfdba6a |
| Issue introduced in 5.0 with commit d2b4387f3bdf016e266d23cf657465f557721488 and fixed in 5.12.4 with commit 75321dc8aebe3f30eff226028fe6da340fe0bf02 |
| Issue introduced in 5.0 with commit d2b4387f3bdf016e266d23cf657465f557721488 and fixed in 5.13 with commit 3536169f8531c2c5b153921dc7d1ac9fd570cda7 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2020-36787 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/clk/clk-ast2600.c |
| drivers/media/platform/aspeed-video.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/1dc1d30ac101bb8335d9852de2107af60c2580e7 |
| https://git.kernel.org/stable/c/a59d01384c80a8a4392665802df57c3df20055f5 |
| https://git.kernel.org/stable/c/2964c37563e86cfdc439f217eb3c5a69adfdba6a |
| https://git.kernel.org/stable/c/75321dc8aebe3f30eff226028fe6da340fe0bf02 |
| https://git.kernel.org/stable/c/3536169f8531c2c5b153921dc7d1ac9fd570cda7 |
