Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h
index 131ea1b..f3caeeb 100644
--- a/include/linux/tpm_eventlog.h
+++ b/include/linux/tpm_eventlog.h
@@ -81,6 +81,8 @@
 	u16 digest_size;
 } __packed;
 
+#define TCG_SPECID_SIG "Spec ID Event03"
+
 struct tcg_efi_specid_event_head {
 	u8 signature[16];
 	u32 platform_class;
@@ -171,6 +173,7 @@
 	int i;
 	int j;
 	u32 count, event_type;
+	const u8 zero_digest[sizeof(event_header->digest)] = {0};
 
 	marker = event;
 	marker_start = marker;
@@ -198,10 +201,26 @@
 	count = READ_ONCE(event->count);
 	event_type = READ_ONCE(event->event_type);
 
+	/* Verify that it's the log header */
+	if (event_header->pcr_idx != 0 ||
+	    event_header->event_type != NO_ACTION ||
+	    memcmp(event_header->digest, zero_digest, sizeof(zero_digest))) {
+		size = 0;
+		goto out;
+	}
+
 	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;
 
-	/* Check if event is malformed. */
-	if (count > efispecid->num_algs) {
+	/*
+	 * Perform validation of the event in order to identify malformed
+	 * events. This function may be asked to parse arbitrary byte sequences
+	 * immediately following a valid event log. The caller expects this
+	 * function to recognize that the byte sequence is not a valid event
+	 * and to return an event size of 0.
+	 */
+	if (memcmp(efispecid->signature, TCG_SPECID_SIG,
+		   sizeof(TCG_SPECID_SIG)) ||
+	    !efispecid->num_algs || count != efispecid->num_algs) {
 		size = 0;
 		goto out;
 	}