libext2fs: fix bounds check of the bitmap test range in get_free_blocks2

[tools/e2fsprogs.git] / lib / ext2fs / alloc.c

diff --git a/lib/ext2fs/alloc.c b/lib/ext2fs/alloc.c
index 0acbc4e..2061b9d 100644 (file)
--- a/lib/ext2fs/alloc.c
+++ b/lib/ext2fs/alloc.c
@@ -257,8 +257,11 @@ errcode_t ext2fs_get_free_blocks2(ext2_filsys fs, blk64_t start, blk64_t finish,
        b &= ~(c_ratio - 1);
        finish &= ~(c_ratio -1);
        do {
-               if (b+num-1 > ext2fs_blocks_count(fs->super))
+               if (b + num - 1 >= ext2fs_blocks_count(fs->super)) {
+                       if (finish > start)
+                               return EXT2_ET_BLOCK_ALLOC_FAIL;
                        b = fs->super->s_first_data_block;
+               }
                if (ext2fs_fast_test_block_bitmap_range2(map, b, num)) {
                        *ret = b;
                        return 0;