Incremental Ext4 Bug: prevent out of bound boundary allocations

This happens around the boundary of block groups where a slightly
different block boundary is set based on size of filesystem which means
allocations based on a previous filesystem layout need to verify they're
not crossing that new bounday

BUG: 27698960
Change-Id: I45d444b4477f14f71e8f17144523505a7525b4e2
Signed-off-by: Mohamad Ayyash <mkayyash@google.com>

diff --git a/ext4_utils/make_ext4fs.c b/ext4_utils/make_ext4fs.c
index 6083cea..f45a699 100644 (file)
--- a/ext4_utils/make_ext4fs.c
+++ b/ext4_utils/make_ext4fs.c
@@ -617,10 +617,6 @@ static void extract_base_fs_allocations(const char *directory, const char *mount
                                } else {
                                        end_block = parse_num(range);
                                }
-                               block_file_size = end_block - start_block + 1;
-                               if (block_file_size > real_file_block_size) {
-                                       block_file_size = real_file_block_size;
-                               }
                                // Assummption is that allocations are within the same block group
                                block_group = get_block_group(start_block);
                                if (block_group != get_block_group(end_block)) {
@@ -628,6 +624,18 @@ static void extract_base_fs_allocations(const char *directory, const char *mount
                                                                   "block group than start block. did you change fs params?");
                                }
                                block_range = strtok_r(NULL, ",", &end_string);
+                               int bg_first_block = bgs[block_group].first_block;
+                               int min_bg_bound = bgs[block_group].chunks[0].block + bgs[block_group].chunks[0].len;
+                               int max_bg_bound = bgs[block_group].chunks[bgs[block_group].chunk_count - 1].block;
+
+                               if (min_bg_bound >= start_block - bg_first_block ||
+                                       max_bg_bound <= end_block - bg_first_block) {
+                                       continue;
+                               }
+                               block_file_size = end_block - start_block + 1;
+                               if (block_file_size > real_file_block_size) {
+                                       block_file_size = real_file_block_size;
+                               }
                                append_region(fs_alloc, start_block, block_file_size, block_group);
                                reserve_bg_chunk(block_group, start_block - bgs[block_group].first_block, block_file_size);
                                real_file_block_size -= block_file_size;