[PATCH v1] ACPI: bus: Adjust acpi_osc_handshake() parameter list

["Rafael J. Wysocki" <rafael@kernel.org>]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

For the sake of interface cleanliness, it is better to avoid using
ACPICA data types in the parameter lists of helper functions that
don't belong to ACPICA, so adjust the parameter list of recently
introduced acpi_osc_handshake() to take a capabilities buffer pointer
and the size of the buffer (in u32 size units) as parameters directly
instead of a struct acpi_buffer pointer.

This is also somewhat more straightforward on the caller side because
they won't need to create struct acpi_buffer objects themselves to pass
them to the helper function and it guarantees that the size of the
buffer in bytes will always be a multiple of 4 (the size of u32).

Moreover, it addresses a premature cap pointer dereference and
eliminates a sizeof(32) that should have been sizeof(u32) [1].

Fixes: e5322888e6bf ("ACPI: bus: Rework the handling of \_SB._OSC platform features")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-acpi/202512242052.W4GhDauV-lkp@intel.com/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/bus.c |   30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -326,31 +326,33 @@ out:
 EXPORT_SYMBOL(acpi_run_osc);
 
 static int acpi_osc_handshake(acpi_handle handle, const char *uuid_str,
-			      int rev, struct acpi_buffer *cap)
+			      int rev, u32 *capbuf, size_t bufsize)
 {
 	union acpi_object in_params[4], *out_obj;
-	size_t bufsize = cap->length / sizeof(u32);
 	struct acpi_object_list input;
+	struct acpi_buffer cap = {
+		.pointer = capbuf,
+		.length = bufsize * sizeof(32),
+	};
 	struct acpi_buffer output;
-	u32 *capbuf, *retbuf, test;
+	u32 *retbuf, test;
 	guid_t guid;
 	int ret, i;
 
-	if (!cap || cap->length < 2 * sizeof(32) || guid_parse(uuid_str, &guid))
+	if (!capbuf || bufsize < 2 || guid_parse(uuid_str, &guid))
 		return -EINVAL;
 
 	/* First evaluate _OSC with OSC_QUERY_ENABLE set. */
-	capbuf = cap->pointer;
 	capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
 
-	ret = acpi_eval_osc(handle, &guid, rev, cap, in_params, &output);
+	ret = acpi_eval_osc(handle, &guid, rev, &cap, in_params, &output);
 	if (ret)
 		return ret;
 
 	out_obj = output.pointer;
 	retbuf = (u32 *)out_obj->buffer.pointer;
 
-	if (acpi_osc_error_check(handle, &guid, rev, cap, retbuf)) {
+	if (acpi_osc_error_check(handle, &guid, rev, &cap, retbuf)) {
 		ret = -ENODATA;
 		goto out;
 	}
@@ -403,7 +405,7 @@ static int acpi_osc_handshake(acpi_handl
 		 */
 		acpi_handle_err(handle, "_OSC: errors while processing control request\n");
 		acpi_handle_err(handle, "_OSC: some features may be missing\n");
-		acpi_osc_error_check(handle, &guid, rev, cap, retbuf);
+		acpi_osc_error_check(handle, &guid, rev, &cap, retbuf);
 	}
 
 out:
@@ -446,10 +448,6 @@ static void acpi_bus_osc_negotiate_platf
 {
 	static const u8 sb_uuid_str[] = "0811B06E-4A27-44F9-8D60-3CBBC22E7B48";
 	u32 capbuf[2], feature_mask;
-	struct acpi_buffer cap = {
-		.pointer = capbuf,
-		.length = sizeof(capbuf),
-	};
 	acpi_handle handle;
 
 	feature_mask = OSC_SB_PR3_SUPPORT | OSC_SB_HOTPLUG_OST_SUPPORT |
@@ -497,7 +495,7 @@ static void acpi_bus_osc_negotiate_platf
 
 	acpi_handle_info(handle, "platform _OSC: OS support mask [%08x]\n", feature_mask);
 
-	if (acpi_osc_handshake(handle, sb_uuid_str, 1, &cap))
+	if (acpi_osc_handshake(handle, sb_uuid_str, 1, capbuf, 2))
 		return;
 
 	feature_mask = capbuf[OSC_SUPPORT_DWORD];
@@ -532,10 +530,6 @@ static void acpi_bus_osc_negotiate_usb_c
 {
 	static const u8 sb_usb_uuid_str[] = "23A0D13A-26AB-486C-9C5F-0FFA525A575A";
 	u32 capbuf[3], control;
-	struct acpi_buffer cap = {
-		.pointer = capbuf,
-		.length = sizeof(capbuf),
-	};
 	acpi_handle handle;
 
 	if (!osc_sb_native_usb4_support_confirmed)
@@ -550,7 +544,7 @@ static void acpi_bus_osc_negotiate_usb_c
 	capbuf[OSC_SUPPORT_DWORD] = 0;
 	capbuf[OSC_CONTROL_DWORD] = control;
 
-	if (acpi_osc_handshake(handle, sb_usb_uuid_str, 1, &cap))
+	if (acpi_osc_handshake(handle, sb_usb_uuid_str, 1, capbuf, 3))
 		return;
 
 	osc_sb_native_usb4_control = capbuf[OSC_CONTROL_DWORD];