ACPI: APEI: EINJ: Fix EINJV2 initialization and injection

ACPI 6.6 specification for EINJV2 appends an extra structure to
the end of the existing struct set_error_type_with_address.

Several issues showed up in testing.

 1) Initialization was broken by an earlier fix [1] since is_v2 is only
    set while performing an injection, not during initialization.

 2) A buggy BIOS provided invalid "revision" and "length" for the
    extension structure. Add several sanity checks.

 3) When injecting legacy error types on an EINJV2 capable system,
    don't copy the component arrays.

Fixes: 6c70585 ("ACPI: APEI: EINJ: Check if user asked for EINJV2 injection") # [1]
Fixes: b476102 ("ACPI: APEI: EINJ: Enable EINJv2 error injections")
Signed-off-by: Tony Luck <[email protected]>
[ rjw: Changelog edits ]
Cc: 6.17+ <[email protected]> # 6.17+
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: aegl

drivers/acpi/apei/einj-core.c

@@ -182,6 +182,7 @@ bool einj_initialized __ro_after_init;
 
 static void __iomem *einj_param;
 static u32 v5param_size;
+static u32 v66param_size;
 static bool is_v2;
 
 static void einj_exec_ctx_init(struct apei_exec_context *ctx)
@@ -283,6 +284,24 @@ static void check_vendor_extension(u64 paddr,
 	acpi_os_unmap_iomem(p, sizeof(v));
 }
 
+static u32 einjv2_init(struct einjv2_extension_struct *e)
+{
+	if (e->revision != 1) {
+		pr_info("Unknown v2 extension revision %u\n", e->revision);
+		return 0;
+	}
+	if (e->length < sizeof(*e) || e->length > PAGE_SIZE) {
+		pr_info(FW_BUG "Bad1 v2 extension length %u\n", e->length);
+		return 0;
+	}
+	if ((e->length - sizeof(*e)) % sizeof(e->component_arr[0])) {
+		pr_info(FW_BUG "Bad2 v2 extension length %u\n", e->length);
+		return 0;
+	}
+
+	return (e->length - sizeof(*e)) / sizeof(e->component_arr[0]);
+}
+
 static void __iomem *einj_get_parameter_address(void)
 {
 	int i;
@@ -310,28 +329,21 @@ static void __iomem *einj_get_parameter_address(void)
 		v5param_size = sizeof(v5param);
 		p = acpi_os_map_iomem(pa_v5, sizeof(*p));
 		if (p) {
-			int offset, len;
-
 			memcpy_fromio(&v5param, p, v5param_size);
 			acpi5 = 1;
 			check_vendor_extension(pa_v5, &v5param);
-			if (is_v2 && available_error_type & ACPI65_EINJV2_SUPP) {
-				len = v5param.einjv2_struct.length;
-				offset = offsetof(struct einjv2_extension_struct, component_arr);
-				max_nr_components = (len - offset) /
-						sizeof(v5param.einjv2_struct.component_arr[0]);
-				/*
-				 * The first call to acpi_os_map_iomem above does not include the
-				 * component array, instead it is used to read and calculate maximum
-				 * number of components supported by the system. Below, the mapping
-				 * is expanded to include the component array.
-				 */
+			if (available_error_type & ACPI65_EINJV2_SUPP) {
+				struct einjv2_extension_struct *e;
+
+				e = &v5param.einjv2_struct;
+				max_nr_components = einjv2_init(e);
+
+				/* remap including einjv2_extension_struct */
 				acpi_os_unmap_iomem(p, v5param_size);
-				offset = offsetof(struct set_error_type_with_address, einjv2_struct);
-				v5param_size = offset + struct_size(&v5param.einjv2_struct,
-					component_arr, max_nr_components);
-				p = acpi_os_map_iomem(pa_v5, v5param_size);
+				v66param_size = v5param_size - sizeof(*e) + e->length;
+				p = acpi_os_map_iomem(pa_v5, v66param_size);
 			}
+
 			return p;
 		}
 	}
@@ -527,6 +539,7 @@ static int __einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 			       u64 param3, u64 param4)
 {
 	struct apei_exec_context ctx;
+	u32 param_size = is_v2 ? v66param_size : v5param_size;
 	u64 val, trigger_paddr, timeout = FIRMWARE_TIMEOUT;
 	int i, rc;
 
@@ -539,11 +552,11 @@ static int __einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 	if (acpi5) {
 		struct set_error_type_with_address *v5param;
 
-		v5param = kmalloc(v5param_size, GFP_KERNEL);
+		v5param = kmalloc(param_size, GFP_KERNEL);
 		if (!v5param)
 			return -ENOMEM;
 
-		memcpy_fromio(v5param, einj_param, v5param_size);
+		memcpy_fromio(v5param, einj_param, param_size);
 		v5param->type = type;
 		if (type & ACPI5_VENDOR_BIT) {
 			switch (vendor_flags) {
@@ -601,7 +614,7 @@ static int __einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 				break;
 			}
 		}
-		memcpy_toio(einj_param, v5param, v5param_size);
+		memcpy_toio(einj_param, v5param, param_size);
 		kfree(v5param);
 	} else {
 		rc = apei_exec_run(&ctx, ACPI_EINJ_SET_ERROR_TYPE);
@@ -1132,9 +1145,14 @@ static void einj_remove(struct faux_device *fdev)
 	struct apei_exec_context ctx;
 
 	if (einj_param) {
-		acpi_size size = (acpi5) ?
-			v5param_size :
-			sizeof(struct einj_parameter);
+		acpi_size size;
+
+		if (v66param_size)
+			size = v66param_size;
+		else if (acpi5)
+			size = v5param_size;
+		else
+			size = sizeof(struct einj_parameter);
 
 		acpi_os_unmap_iomem(einj_param, size);
 		if (vendor_errors.size)