diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
index 07f9d66d0..8d08689e2 100644
--- a/fs_mgr/liblp/builder.cpp
+++ b/fs_mgr/liblp/builder.cpp
@@ -267,6 +267,11 @@ void MetadataBuilder::ImportExtents(Partition* dest, const LpMetadata& metadata,
 }
 
 static bool VerifyDeviceProperties(const BlockDeviceInfo& device_info) {
+    if (device_info.logical_block_size == 0) {
+        LERROR << "Block device " << device_info.partition_name
+               << " logical block size must not be zero.";
+        return false;
+    }
     if (device_info.logical_block_size % LP_SECTOR_SIZE != 0) {
         LERROR << "Block device " << device_info.partition_name
                << " logical block size must be a multiple of 512.";
@@ -333,7 +338,7 @@ bool MetadataBuilder::Init(const std::vector<BlockDeviceInfo>& block_devices,
         out.alignment = device_info.alignment;
         out.alignment_offset = device_info.alignment_offset;
         out.size = device_info.size;
-        if (device_info.partition_name.size() >= sizeof(out.partition_name)) {
+        if (device_info.partition_name.size() > sizeof(out.partition_name)) {
             LERROR << "Partition name " << device_info.partition_name << " exceeds maximum length.";
             return false;
         }
diff --git a/fs_mgr/liblp/include/liblp/metadata_format.h b/fs_mgr/liblp/include/liblp/metadata_format.h
index 9c5ec5c93..8934aaff2 100644
--- a/fs_mgr/liblp/include/liblp/metadata_format.h
+++ b/fs_mgr/liblp/include/liblp/metadata_format.h
@@ -127,7 +127,7 @@ typedef struct LpMetadataGeometry {
  * num_entries, and the result must not overflow a 32-bit signed integer.
  */
 typedef struct LpMetadataTableDescriptor {
-    /*  0: Location of the table, relative to the metadata header. */
+    /*  0: Location of the table, relative to end of the metadata header. */
     uint32_t offset;
     /*  4: Number of entries in the table. */
     uint32_t num_entries;
@@ -272,7 +272,7 @@ typedef struct LpMetadataPartitionGroup {
 
     /* 40: Maximum size in bytes. If 0, the group has no maximum size. */
     uint64_t maximum_size;
-} LpMetadataPartitionGroup;
+} __attribute__((packed)) LpMetadataPartitionGroup;
 
 /* This flag is only intended to be used with super_empty.img and super.img on
  * retrofit devices. If set, the group needs a slot suffix to be interpreted
@@ -323,7 +323,7 @@ typedef struct LpMetadataBlockDevice {
 
     /* 60: Flags (see LP_BLOCK_DEVICE_* flags below). */
     uint32_t flags;
-} LpMetadataBlockDevice;
+} __attribute__((packed)) LpMetadataBlockDevice;
 
 /* This flag is only intended to be used with super_empty.img and super.img on
  * retrofit devices. On these devices there are A and B super partitions, and
diff --git a/fs_mgr/liblp/reader.cpp b/fs_mgr/liblp/reader.cpp
index 24c6b2c31..dcee6d2d8 100644
--- a/fs_mgr/liblp/reader.cpp
+++ b/fs_mgr/liblp/reader.cpp
@@ -256,6 +256,10 @@ static std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geome
             LERROR << "Logical partition has invalid attribute set.";
             return nullptr;
         }
+        if (partition.first_extent_index + partition.num_extents < partition.first_extent_index) {
+            LERROR << "Logical partition first_extent_index + num_extents overflowed.";
+            return nullptr;
+        }
         if (partition.first_extent_index + partition.num_extents > header.extents.num_entries) {
             LERROR << "Logical partition has invalid extent list.";
             return nullptr;
diff --git a/fs_mgr/liblp/writer.cpp b/fs_mgr/liblp/writer.cpp
index 454258b75..0ab0d8cf6 100644
--- a/fs_mgr/liblp/writer.cpp
+++ b/fs_mgr/liblp/writer.cpp
@@ -367,11 +367,11 @@ bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& sup
         // safety.
         std::string old_blob;
         if (!ValidateAndSerializeMetadata(opener, *backup.get(), slot_suffix, &old_blob)) {
-            LERROR << "Error serializing primary metadata to repair corrupted backup";
+            LERROR << "Error serializing backup metadata to repair corrupted primary";
             return false;
         }
         if (!WritePrimaryMetadata(fd, metadata, slot_number, old_blob, writer)) {
-            LERROR << "Error writing primary metadata to repair corrupted backup";
+            LERROR << "Error writing backup metadata to repair corrupted primary";
             return false;
         }
     }