replay-log: add validations for corrupt log entries

Check for all zeros entry and for non zero padded entry
and report log offset of corrupted log entry.

Also report log offsets with -v and -vv debug prints.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>

src/log-writes/log-writes.c

@@ -117,6 +117,26 @@ int log_discard(struct log *log, struct log_write_entry *entry)
 	return 0;
 }
 
+/*
+ * @entry: entry to be replayed.
+ *
+ * @return: 1 if the entry is sane, 0 if it is invalid.
+ *
+ * Check if this is a sane log entry.
+ */
+int log_entry_valid(struct log_write_entry *entry)
+{
+	u64 flags = le64_to_cpu(entry->flags);
+
+	/* Suspect all zeroes entry */
+	if (!flags && !entry->nr_sectors)
+		return 0;
+	/* Suspect non zero padded entry */
+	if (flags != LOG_MARK_FLAG && entry->data[0] != 0)
+		return 0;
+	return 1;
+}
+
 /*
  * @log: the log we are replaying.
  * @entry: where we put the entry.
@@ -141,11 +161,16 @@ int log_replay_next_entry(struct log *log, struct log_write_entry *entry,
 	if (log->cur_entry >= log->nr_entries)
 		return 1;
 
+	offset = lseek(log->logfd, 0, SEEK_CUR);
 	ret = read(log->logfd, entry, read_size);
 	if (ret != read_size) {
 		fprintf(stderr, "Error reading entry: %d\n", errno);
 		return -1;
 	}
+	if (!log_entry_valid(entry)) {
+		fprintf(stderr, "Malformed entry @%llu\n", offset / log->sectorsize);
+		return -1;
+	}
 	log->cur_entry++;
 
 	size = le64_to_cpu(entry->nr_sectors) * log->sectorsize;
@@ -158,12 +183,13 @@ int log_replay_next_entry(struct log *log, struct log_write_entry *entry,
 		}
 	}
 
-	if (log_writes_verbose)
-		printf("replaying %d: sector %llu, size %llu, flags %llu\n",
-		       (int)log->cur_entry - 1,
+	if (log_writes_verbose) {
+		printf("replaying %d@%llu: sector %llu, size %llu, flags %llu\n",
+		       (int)log->cur_entry - 1, offset / log->sectorsize,
 		       (unsigned long long)le64_to_cpu(entry->sector),
 		       (unsigned long long)size,
 		       (unsigned long long)le64_to_cpu(entry->flags));
+	}
 	if (!size)
 		return 0;
 
@@ -221,15 +247,20 @@ int log_seek_entry(struct log *log, u64 entry_num)
 		ssize_t ret;
 		off_t seek_size;
 		u64 flags;
+		off_t offset = lseek(log->logfd, 0, SEEK_CUR);
 
 		ret = read(log->logfd, &entry, sizeof(entry));
 		if (ret != sizeof(entry)) {
 			fprintf(stderr, "Error reading entry: %d\n", errno);
 			return -1;
 		}
+		if (!log_entry_valid(&entry)) {
+			fprintf(stderr, "Malformed entry @%llu\n", offset / log->sectorsize);
+			return -1;
+		}
 		if (log_writes_verbose > 1)
-			printf("seek entry %d: %llu, size %llu, flags %llu\n",
-			       (int)i,
+			printf("seek entry %d@%llu: %llu, size %llu, flags %llu\n",
+			       (int)i, offset / log->sectorsize,
 			       (unsigned long long)le64_to_cpu(entry.sector),
 			       (unsigned long long)le64_to_cpu(entry.nr_sectors),
 			       (unsigned long long)le64_to_cpu(entry.flags));
@@ -264,17 +295,23 @@ int log_seek_next_entry(struct log *log, struct log_write_entry *entry,
 {
 	size_t read_size = read_data ? log->sectorsize :
 		sizeof(struct log_write_entry);
+	off_t offset;
 	u64 flags;
 	ssize_t ret;
 
 	if (log->cur_entry >= log->nr_entries)
 		return 1;
 
+	offset = lseek(log->logfd, 0, SEEK_CUR);
 	ret = read(log->logfd, entry, read_size);
 	if (ret != read_size) {
 		fprintf(stderr, "Error reading entry: %d\n", errno);
 		return -1;
 	}
+	if (!log_entry_valid(entry)) {
+		fprintf(stderr, "Malformed entry @%llu\n", offset / log->sectorsize);
+		return -1;
+	}
 	log->cur_entry++;
 
 	if (read_size < log->sectorsize) {
@@ -286,14 +323,14 @@ int log_seek_next_entry(struct log *log, struct log_write_entry *entry,
 		}
 	}
 	if (log_writes_verbose > 1)
-		printf("seek entry %d: %llu, size %llu, flags %llu\n",
-		       (int)log->cur_entry - 1,
+		printf("seek entry %d@%llu: %llu, size %llu, flags %llu\n",
+		       (int)log->cur_entry - 1, offset / log->sectorsize,
 		       (unsigned long long)le64_to_cpu(entry->sector),
 		       (unsigned long long)le64_to_cpu(entry->nr_sectors),
 		       (unsigned long long)le64_to_cpu(entry->flags));
 
-	flags = le32_to_cpu(entry->flags);
-	read_size = le32_to_cpu(entry->nr_sectors) * log->sectorsize;
+	flags = le64_to_cpu(entry->flags);
+	read_size = le64_to_cpu(entry->nr_sectors) * log->sectorsize;
 	if (!read_size || (flags & LOG_DISCARD_FLAG))
 		return 0;
 

src/log-writes/log-writes.h

@@ -43,6 +43,7 @@ struct log_write_entry {
 	__le64 nr_sectors;
 	__le64 flags;
 	__le64 data_len;
+	char data[1];
 };
 
 #define LOG_IGNORE_DISCARD (1 << 0)

src/log-writes/replay-log.c

@@ -69,7 +69,7 @@ static int should_stop(struct log_write_entry *entry, u64 stop_flags,
 {
 	u64 flags = le64_to_cpu(entry->flags);
 	int check_mark = (stop_flags & LOG_MARK_FLAG);
-	char *buf = (char *)(entry + 1);
+	char *buf = entry->data;
 
 	if (flags & stop_flags) {
 		if (!check_mark)
@@ -284,8 +284,10 @@ int main(int argc, char **argv)
 			num_entries++;
 			if ((run_limit && num_entries == run_limit) ||
 			    should_stop(entry, stop_flags, end_mark)) {
-				printf("%llu\n",
-				       (unsigned long long)log->cur_entry - 1);
+				off_t offset = lseek(log->logfd, 0, SEEK_CUR);
+
+				printf("%llu@%llu\n",
+				       (unsigned long long)log->cur_entry - 1, offset / log->sectorsize);
 				log_free(log);
 				return 0;
 			}