From 4605a35d1ef573dc166a73ed910d0ee7b02489cb Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Tue, 8 Oct 2013 11:51:23 -0400 Subject: [PATCH] libext2fs: fix off-by-one error in file truncation When told to truncate a file, ext2fs_file_set_size2() should start with the first block past the end of the file. The current calculation jumps one more block ahead, with the result that it fails to hack off the last block. Adding blocksize-1 and dividing is sufficient to find the last block. Reviewed-by: Lukas Czerner Signed-off-by: Darrick J. Wong Signed-off-by: "Theodore Ts'o" --- lib/ext2fs/fileio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c index 059bda2dc..02e626341 100644 --- a/lib/ext2fs/fileio.c +++ b/lib/ext2fs/fileio.c @@ -393,10 +393,10 @@ errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size) EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); truncate_block = ((size + file->fs->blocksize - 1) >> - EXT2_BLOCK_SIZE_BITS(file->fs->super)) + 1; + EXT2_BLOCK_SIZE_BITS(file->fs->super)); old_size = EXT2_I_SIZE(&file->inode); old_truncate = ((old_size + file->fs->blocksize - 1) >> - EXT2_BLOCK_SIZE_BITS(file->fs->super)) + 1; + EXT2_BLOCK_SIZE_BITS(file->fs->super)); /* If we're writing a large file, set the large_file flag */ if (LINUX_S_ISREG(file->inode.i_mode) && -- 2.47.2