Revert "vboot: update get system properties"

This reverts commit 8ef4f7a9a9a68bad49e8417d5ed346dc927e1d2c.

Reason for revert: Installer supposedly misuses API with
`VbGetSystemPropertyString("fw_try_next", NULL, 0);`
by passing a `NULL` ptr as dest and so not sized.

The call sites need checking.

BUG=b:280417931
TEST=none

Original change's description:
> vboot: update get system properties
>
> `VbGetSystemPropertyString` header promises that the property string
> will be read into the passed in dest buffer, however for some system
> properties the values are not placed in buffer but returned directly.
> this patch fixes that error
>
> Before, running `VbGetSystemPropertyString("minios_priority", buf,
> size):`
> ```
> buf:  return value: B
> ```
> After, same command:
> ```
> buf: B return value: B
> ```
>
> BRANCH=none
> BUG=none
> TEST=Tested with an executable on brya
>
> Signed-off-by: Saketh Pothireddy <spothire@chromium.org>
>
> Change-Id: I87a0aa8638e719bc5bbea579ecaca4754a38c02e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4468208
> Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
> Reviewed-by: Julius Werner <jwerner@chromium.org>
> Commit-Queue: Saketh Pothireddy <spothire@google.com>
> Tested-by: Saketh Pothireddy <spothire@google.com>

Bug: none
Change-Id: Ie07363424db92832b485c9efae21edbf0d24fba5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4508974
Commit-Queue: Edward O'Callaghan <quasisec@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Edward O'Callaghan <quasisec@chromium.org>

1 files changed, 12 insertions, 16 deletions

diff --git a/host/lib/crossystem.c b/host/lib/crossystem.c
index 24449b91..a7b04b99 100644
--- a/host/lib/crossystem.c
+++ b/host/lib/crossystem.c
@@ -536,9 +536,9 @@ const char *VbGetSystemPropertyString(const char *name, char *dest, size_t size)
 	if (!strcasecmp(name,"kernkey_vfy")) {
 		switch(GetVdatInt(VDAT_INT_KERNEL_KEY_VERIFIED)) {
 			case 0:
-				return StrCopy(dest, "hash", size);
+				return "hash";
 			case 1:
-				return StrCopy(dest, "sig", size);
+				return "sig";
 			default:
 				return NULL;
 		}
@@ -548,35 +548,31 @@ const char *VbGetSystemPropertyString(const char *name, char *dest, size_t size)
 		return GetVdatString(dest, size,
 				     VDAT_STRING_LOAD_FIRMWARE_DEBUG);
 	} else if (!strcasecmp(name, "fw_try_next")) {
-		return StrCopy(dest, vb2_get_nv_storage(VB2_NV_TRY_NEXT) ?
-						"B" : "A", size);
+		return vb2_get_nv_storage(VB2_NV_TRY_NEXT) ? "B" : "A";
 	} else if (!strcasecmp(name, "fw_tried")) {
-		return StrCopy(dest, vb2_get_nv_storage(VB2_NV_FW_TRIED) ?
-						"B" : "A", size);
+		return vb2_get_nv_storage(VB2_NV_FW_TRIED) ? "B" : "A";
 	} else if (!strcasecmp(name, "fw_result")) {
 		int v = vb2_get_nv_storage(VB2_NV_FW_RESULT);
 		if (v < ARRAY_SIZE(fw_results))
-			return StrCopy(dest, fw_results[v], size);
+			return fw_results[v];
 		else
-			return StrCopy(dest, "unknown", size);
+			return "unknown";
 	} else if (!strcasecmp(name, "fw_prev_tried")) {
-		return StrCopy(dest, vb2_get_nv_storage(VB2_NV_FW_PREV_TRIED) ?
-						"B" : "A", size);
+		return vb2_get_nv_storage(VB2_NV_FW_PREV_TRIED) ? "B" : "A";
 	} else if (!strcasecmp(name, "fw_prev_result")) {
 		int v = vb2_get_nv_storage(VB2_NV_FW_PREV_RESULT);
 		if (v < ARRAY_SIZE(fw_results))
-			return StrCopy(dest, fw_results[v], size);
+			return fw_results[v];
 		else
-			return StrCopy(dest, "unknown", size);
+			return "unknown";
 	} else if (!strcasecmp(name,"dev_default_boot")) {
 		int v = vb2_get_nv_storage(VB2_NV_DEV_DEFAULT_BOOT);
 		if (v < ARRAY_SIZE(default_boot))
-			return StrCopy(dest, default_boot[v], size);
+			return default_boot[v];
 		else
-			return StrCopy(dest, "unknown", size);
+			return "unknown";
 	} else if (!strcasecmp(name, "minios_priority")) {
-		return StrCopy(dest, vb2_get_nv_storage(VB2_NV_MINIOS_PRIORITY)
-						? "B" : "A", size);
+		return vb2_get_nv_storage(VB2_NV_MINIOS_PRIORITY) ? "B" : "A";
 	}
 
 	return NULL;