gpiolib: acpi: Fix potential out-of-boundary left shift

andy-shev · gregkh · commit f749b366b8e7 · 2026-02-06T16:57:44.000+01:00
commit e64d1cb upstream. GPIO Address Space handler gets a pointer to the in or out value. This value is supposed to be at least 64-bit, but it's not limited to be exactly 64-bit. When ACPI tables are being parsed, for the bigger Connection():s ACPICA creates a Buffer instead of regular Integer object. The Buffer exists as long as Namespace holds the certain Connection(). Hence we can access the necessary bits without worrying. On the other hand, the left shift, used in the code, is limited by 31 (on 32-bit platforms) and otherwise considered to be Undefined Behaviour. Also the code uses only the first 64-bit word for the value, and anything bigger than 63 will be also subject to UB. Fix all this by modifying the code to correctly set or clear the respective bit in the bitmap constructed of 64-bit words. Fixes: 59084c564c41 ("gpiolib: acpi: use BIT_ULL() for u64 mask in address space handler") Fixes: 2c4d00c ("gpiolib: acpi: Use BIT() macro to increase readability") Cc: stable@vger.kernel.org Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20260128095918.4157491-1-andriy.shevchenko@linux.intel.com Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/gpio/gpiolib-acpi-core.c b/drivers/gpio/gpiolib-acpi-core.c
@@ -1104,6 +1104,7 @@ acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
 		unsigned int pin = agpio->pin_table[i];
 		struct acpi_gpio_connection *conn;
 		struct gpio_desc *desc;
+		u16 word, shift;
 		bool found;
 
 		mutex_lock(&achip->conn_lock);
@@ -1158,10 +1159,22 @@ acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
 
 		mutex_unlock(&achip->conn_lock);
 
-		if (function == ACPI_WRITE)
-			gpiod_set_raw_value_cansleep(desc, !!(*value & BIT_ULL(i)));
-		else
-			*value |= (u64)gpiod_get_raw_value_cansleep(desc) << i;
+		/*
+		 * For the cases when OperationRegion() consists of more than
+		 * 64 bits calculate the word and bit shift to use that one to
+		 * access the value.
+		 */
+		word = i / 64;
+		shift = i % 64;
+
+		if (function == ACPI_WRITE) {
+			gpiod_set_raw_value_cansleep(desc, value[word] & BIT_ULL(shift));
+		} else {
+			if (gpiod_get_raw_value_cansleep(desc))
+				value[word] |= BIT_ULL(shift);
+			else
+				value[word] &= ~BIT_ULL(shift);
+		}
 	}
 
 out:
