RE: [PATCH v5] drm/ast: Fixed CVE for DP501

From: Kuo-Hsiang Chou
Date: Thu Apr 29 2021 - 05:22:08 EST

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-----Original Message-----
From: Thomas Zimmermann [mailto:tzimmermann@xxxxxxx]
Sent: Tuesday, April 27, 2021 7:02 PM
To: Kuo-Hsiang Chou <kuohsiang_chou@xxxxxxxxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx

Subject: Re: [PATCH v5] drm/ast: Fixed CVE for DP501

Hi Thomas,
Hi

Am 21.04.21 um 10:58 schrieb KuoHsiang Chou:
> [Bug][DP501]
> If ASPEED P2A (PCI to AHB) bridge is disabled and disallowed for
> CVE_2019_6260 item3, and then the monitor's EDID is unable read
> through Parade DP501.
> The reason is the DP501's FW is mapped to BMC addressing space rather
> than Host addressing space.
> The resolution is that using "pci_iomap_range()" maps to DP501's FW
> that stored on the end of FB (Frame Buffer).
> In this case, FrameBuffer reserves the last 2MB used for the image of
> DP501.
>

Your patches are missing a short changelog, so that reviewers can see what changed between versions. Anyway, I merged your patch into drm-misc-next now. Thanks for the fix.

Thanks, I must keep this rule about the short changelog.

More generally speaking, the DP501 code needs a major refactoring. It's currently bolted onto the regular VGA connector code. It should rather be a separate connector or a DRM bridge. I always wanted to work on this, but don't have a device for testing. If I'd provide patches, would you be in a position to test them?

NO, I can't. The patch was verified on AST2500+DP501 before, so the correctness of this patch is promised. But customer always requested to send the platform back after bug fixed. Now, no DP501 platform on my hand, but I try to convince custom to get the someone platform.

Best Regards,
Kuo-Hsiang Chou

Best regards
Thomas

> Signed-off-by: KuoHsiang Chou <kuohsiang_chou@xxxxxxxxxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> ---
> drivers/gpu/drm/ast/ast_dp501.c | 139 +++++++++++++++++++++++---------
> drivers/gpu/drm/ast/ast_drv.h | 12 +++
> drivers/gpu/drm/ast/ast_main.c | 11 ++-
> 3 files changed, 125 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/gpu/drm/ast/ast_dp501.c
> b/drivers/gpu/drm/ast/ast_dp501.c index 88121c0e0..cd93c44f2 100644
> --- a/drivers/gpu/drm/ast/ast_dp501.c
> +++ b/drivers/gpu/drm/ast/ast_dp501.c
> @@ -189,6 +189,9 @@ bool ast_backup_fw(struct drm_device *dev, u8 *addr, u32 size)
> u32 i, data;
> u32 boot_address;
>
> + if (ast->config_mode != ast_use_p2a)
> + return false;
> +
> data = ast_mindwm(ast, 0x1e6e2100) & 0x01;
> if (data) {
> boot_address = get_fw_base(ast);
> @@ -207,6 +210,9 @@ static bool ast_launch_m68k(struct drm_device *dev)
> u8 *fw_addr = NULL;
> u8 jreg;
>
> + if (ast->config_mode != ast_use_p2a)
> + return false;
> +
> data = ast_mindwm(ast, 0x1e6e2100) & 0x01;
> if (!data) {
>
> @@ -271,25 +277,55 @@ u8 ast_get_dp501_max_clk(struct drm_device *dev)
> struct ast_private *ast = to_ast_private(dev);
> u32 boot_address, offset, data;
> u8 linkcap[4], linkrate, linklanes, maxclk = 0xff;
> + u32 *plinkcap;
>
> - boot_address = get_fw_base(ast);
> -
> - /* validate FW version */
> - offset = 0xf000;
> - data = ast_mindwm(ast, boot_address + offset);
> - if ((data & 0xf0) != 0x10) /* version: 1x */
> - return maxclk;
> -
> - /* Read Link Capability */
> - offset = 0xf014;
> - *(u32 *)linkcap = ast_mindwm(ast, boot_address + offset);
> - if (linkcap[2] == 0) {
> - linkrate = linkcap[0];
> - linklanes = linkcap[1];
> - data = (linkrate == 0x0a) ? (90 * linklanes) : (54 * linklanes);
> - if (data > 0xff)
> - data = 0xff;
> - maxclk = (u8)data;
> + if (ast->config_mode == ast_use_p2a) {
> + boot_address = get_fw_base(ast);
> +
> + /* validate FW version */
> + offset = AST_DP501_GBL_VERSION;
> + data = ast_mindwm(ast, boot_address + offset);
> + if ((data & AST_DP501_FW_VERSION_MASK) != AST_DP501_FW_VERSION_1) /* version: 1x */
> + return maxclk;
> +
> + /* Read Link Capability */
> + offset = AST_DP501_LINKRATE;
> + plinkcap = (u32 *)linkcap;
> + *plinkcap = ast_mindwm(ast, boot_address + offset);
> + if (linkcap[2] == 0) {
> + linkrate = linkcap[0];
> + linklanes = linkcap[1];
> + data = (linkrate == 0x0a) ? (90 * linklanes) : (54 * linklanes);
> + if (data > 0xff)
> + data = 0xff;
> + maxclk = (u8)data;
> + }
> + } else {
> + if (!ast->dp501_fw_buf)
> + return AST_DP501_DEFAULT_DCLK; /* 1024x768 as default */
> +
> + /* dummy read */
> + offset = 0x0000;
> + data = readl(ast->dp501_fw_buf + offset);
> +
> + /* validate FW version */
> + offset = AST_DP501_GBL_VERSION;
> + data = readl(ast->dp501_fw_buf + offset);
> + if ((data & AST_DP501_FW_VERSION_MASK) != AST_DP501_FW_VERSION_1) /* version: 1x */
> + return maxclk;
> +
> + /* Read Link Capability */
> + offset = AST_DP501_LINKRATE;
> + plinkcap = (u32 *)linkcap;
> + *plinkcap = readl(ast->dp501_fw_buf + offset);
> + if (linkcap[2] == 0) {
> + linkrate = linkcap[0];
> + linklanes = linkcap[1];
> + data = (linkrate == 0x0a) ? (90 * linklanes) : (54 * linklanes);
> + if (data > 0xff)
> + data = 0xff;
> + maxclk = (u8)data;
> + }
> }
> return maxclk;
> }
> @@ -298,26 +334,57 @@ bool ast_dp501_read_edid(struct drm_device *dev, u8 *ediddata)
> {
> struct ast_private *ast = to_ast_private(dev);
> u32 i, boot_address, offset, data;
> + u32 *pEDIDidx;
>
> - boot_address = get_fw_base(ast);
> -
> - /* validate FW version */
> - offset = 0xf000;
> - data = ast_mindwm(ast, boot_address + offset);
> - if ((data & 0xf0) != 0x10)
> - return false;
> -
> - /* validate PnP Monitor */
> - offset = 0xf010;
> - data = ast_mindwm(ast, boot_address + offset);
> - if (!(data & 0x01))
> - return false;
> + if (ast->config_mode == ast_use_p2a) {
> + boot_address = get_fw_base(ast);
>
> - /* Read EDID */
> - offset = 0xf020;
> - for (i = 0; i < 128; i += 4) {
> - data = ast_mindwm(ast, boot_address + offset + i);
> - *(u32 *)(ediddata + i) = data;
> + /* validate FW version */
> + offset = AST_DP501_GBL_VERSION;
> + data = ast_mindwm(ast, boot_address + offset);
> + if ((data & AST_DP501_FW_VERSION_MASK) != AST_DP501_FW_VERSION_1)
> + return false;
> +
> + /* validate PnP Monitor */
> + offset = AST_DP501_PNPMONITOR;
> + data = ast_mindwm(ast, boot_address + offset);
> + if (!(data & AST_DP501_PNP_CONNECTED))
> + return false;
> +
> + /* Read EDID */
> + offset = AST_DP501_EDID_DATA;
> + for (i = 0; i < 128; i += 4) {
> + data = ast_mindwm(ast, boot_address + offset + i);
> + pEDIDidx = (u32 *)(ediddata + i);
> + *pEDIDidx = data;
> + }
> + } else {
> + if (!ast->dp501_fw_buf)
> + return false;
> +
> + /* dummy read */
> + offset = 0x0000;
> + data = readl(ast->dp501_fw_buf + offset);
> +
> + /* validate FW version */
> + offset = AST_DP501_GBL_VERSION;
> + data = readl(ast->dp501_fw_buf + offset);
> + if ((data & AST_DP501_FW_VERSION_MASK) != AST_DP501_FW_VERSION_1)
> + return false;
> +
> + /* validate PnP Monitor */
> + offset = AST_DP501_PNPMONITOR;
> + data = readl(ast->dp501_fw_buf + offset);
> + if (!(data & AST_DP501_PNP_CONNECTED))
> + return false;
> +
> + /* Read EDID */
> + offset = AST_DP501_EDID_DATA;
> + for (i = 0; i < 128; i += 4) {
> + data = readl(ast->dp501_fw_buf + offset + i);
> + pEDIDidx = (u32 *)(ediddata + i);
> + *pEDIDidx = data;
> + }
> }
>
> return true;
> diff --git a/drivers/gpu/drm/ast/ast_drv.h
> b/drivers/gpu/drm/ast/ast_drv.h index e82ab8628..911f9f414 100644
> --- a/drivers/gpu/drm/ast/ast_drv.h
> +++ b/drivers/gpu/drm/ast/ast_drv.h
> @@ -150,6 +150,7 @@ struct ast_private {
>
> void __iomem *regs;
> void __iomem *ioregs;
> + void __iomem *dp501_fw_buf;
>
> enum ast_chip chip;
> bool vga2_clone;
> @@ -325,6 +326,17 @@ int ast_mode_config_init(struct ast_private *ast);
> #define AST_MM_ALIGN_SHIFT 4
> #define AST_MM_ALIGN_MASK ((1 << AST_MM_ALIGN_SHIFT) - 1)
>
> +#define AST_DP501_FW_VERSION_MASK GENMASK(7, 4)
> +#define AST_DP501_FW_VERSION_1 BIT(4)
> +#define AST_DP501_PNP_CONNECTED BIT(1)
> +
> +#define AST_DP501_DEFAULT_DCLK 65
> +
> +#define AST_DP501_GBL_VERSION 0xf000
> +#define AST_DP501_PNPMONITOR 0xf010
> +#define AST_DP501_LINKRATE 0xf014
> +#define AST_DP501_EDID_DATA 0xf020
> +
> int ast_mm_init(struct ast_private *ast);
>
> /* ast post */
> diff --git a/drivers/gpu/drm/ast/ast_main.c
> b/drivers/gpu/drm/ast/ast_main.c index 0ac3c2039..3976a2587 100644
> --- a/drivers/gpu/drm/ast/ast_main.c
> +++ b/drivers/gpu/drm/ast/ast_main.c
> @@ -99,7 +99,7 @@ static void ast_detect_config_mode(struct drm_device *dev, u32 *scu_rev)
> if (!(jregd0 & 0x80) || !(jregd1 & 0x10)) {
> /* Double check it's actually working */
> data = ast_read32(ast, 0xf004);
> - if (data != 0xFFFFFFFF) {
> + if ((data != 0xFFFFFFFF) && (data != 0x00)) {
> /* P2A works, grab silicon revision */
> ast->config_mode = ast_use_p2a;
>
> @@ -411,6 +411,7 @@ struct ast_private *ast_device_create(const struct drm_driver *drv,
> return ast;
> dev = &ast->base;
>
> + dev->pdev = pdev;
> pci_set_drvdata(pdev, dev);
>
> ast->regs = pci_iomap(pdev, 1, 0);
> @@ -450,6 +451,14 @@ struct ast_private *ast_device_create(const
> struct
drm_driver *drv,
> if (ret)
> return ERR_PTR(ret);
>
> + /* map reserved buffer */
> + ast->dp501_fw_buf = NULL;
> + if (dev->vram_mm->vram_size < pci_resource_len(dev->pdev, 0)) {
> + ast->dp501_fw_buf = pci_iomap_range(dev->pdev, 0, dev->vram_mm->vram_size, 0);
> + if (!ast->dp501_fw_buf)
> + drm_info(dev, "failed to map reserved buffer!\n");
> + }
> +
> ret = ast_mode_config_init(ast);
> if (ret)
> return ERR_PTR(ret);
> --
> 2.18.4
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

Next message: Mickaël Salaün: "Re: [PATCH v2] samples/landlock: fix path_list memory leak"
Previous message: Neil Armstrong: "Re: [PATCH] clk: meson: axg-audio: do not print error on defer"
In reply to: Thomas Zimmermann: "Re: [PATCH v5] drm/ast: Fixed CVE for DP501"
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