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Commit e2b46574 authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
Browse files

ext4: store maxbytes for bitmapped files and return EFBIG as appropriate 



Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
parent 19295529

fs/ext4/file.c

+18 −1
Original line number Diff line number Diff line
@@ -56,8 +56,25 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov, 
	ssize_t ret;

	int err;



	ret = generic_file_aio_write(iocb, iov, nr_segs, pos);

	/*

	 * If we have encountered a bitmap-format file, the size limit

	 * is smaller than s_maxbytes, which is for extent-mapped files.

	 */



	if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {

		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

		size_t length = iov_length(iov, nr_segs);



		if (pos > sbi->s_bitmap_maxbytes)

			return -EFBIG;



		if (pos + length > sbi->s_bitmap_maxbytes) {

			nr_segs = iov_shorten((struct iovec *)iov, nr_segs,

					      sbi->s_bitmap_maxbytes - pos);

		}

	}



	ret = generic_file_aio_write(iocb, iov, nr_segs, pos);

	/*

	 * Skip flushing if there was an error, or if nothing was written.

	 */

fs/ext4/inode.c

+15 −1
Original line number Diff line number Diff line
@@ -314,7 +314,10 @@ static int ext4_block_to_path(struct inode *inode, 
		offsets[n++] = i_block & (ptrs - 1);

		final = ptrs;

	} else {

		ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");

		ext4_warning(inode->i_sb, "ext4_block_to_path",

				"block %u > max",

				i_block + direct_blocks +

				indirect_blocks + double_blocks);

	}

	if (boundary)

		*boundary = final - 1 - (i_block & (ptrs - 1));
@@ -3092,6 +3095,17 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) 
		ext4_journal_stop(handle);

	}



	if (attr->ia_valid & ATTR_SIZE) {

		if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {

			struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);



			if (attr->ia_size > sbi->s_bitmap_maxbytes) {

				error = -EFBIG;

				goto err_out;

			}

		}

	}



	if (S_ISREG(inode->i_mode) &&

	    attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {

		handle_t *handle;

fs/ext4/super.c

+1 −0
Original line number Diff line number Diff line
@@ -1922,6 +1922,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent) 
		}

	}



	sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits);

	sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits);



	if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {

include/linux/ext4_fs_sb.h

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ struct ext4_sb_info { 
	ext4_group_t s_groups_count;	/* Number of groups in the fs */

	unsigned long s_overhead_last;  /* Last calculated overhead */

	unsigned long s_blocks_last;    /* Last seen block count */

	loff_t s_bitmap_maxbytes;	/* max bytes for bitmap files */

	struct buffer_head * s_sbh;	/* Buffer containing the super block */

	struct ext4_super_block * s_es;	/* Pointer to the super block in the buffer */

	struct buffer_head ** s_group_desc;