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Commit 06a279d6 authored Jan 17, 2009 by Theodore Ts'o

ext4: only use i_size_high for regular files

Directories are not allowed to be bigger than 2GB, so don't use
i_size_high for anything other than regular files.  E2fsck should
complain about these inodes, but the simplest thing to do for the
kernel is to only use i_size_high for regular files.

This prevents an intentially corrupted filesystem from causing the
kernel to burn a huge amount of CPU and issuing error messages such
as:

EXT4-fs warning (device loop0): ext4_block_to_path: block 135090028 > max

Thanks to David Maciejak from Fortinet's FortiGuard Global Security
Research Team for reporting this issue.

http://bugzilla.kernel.org/show_bug.cgi?id=12375



Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

parent c225aa57

fs/ext4/ext4.h

+5 −2

Original line number	Diff line number	Diff line
		@@ -1206,8 +1206,11 @@ static inline void ext4_r_blocks_count_set(struct ext4_super_block *es,

		static inline loff_t ext4_isize(struct ext4_inode *raw_inode)
		{
		if (S_ISREG(le16_to_cpu(raw_inode->i_mode)))
		return ((loff_t)le32_to_cpu(raw_inode->i_size_high) << 32) \|
		le32_to_cpu(raw_inode->i_size_lo);
		else
		return (loff_t) le32_to_cpu(raw_inode->i_size_lo);
		}

		static inline void ext4_isize_set(struct ext4_inode *raw_inode, loff_t i_size)

fs/ext4/inode.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -360,9 +360,9 @@ static int ext4_block_to_path(struct inode *inode,
		final = ptrs;
		} else {
		ext4_warning(inode->i_sb, "ext4_block_to_path",
		"block %lu > max",
		"block %lu > max in inode %lu",
		i_block + direct_blocks +
		indirect_blocks + double_blocks);
		indirect_blocks + double_blocks, inode->i_ino);
		}
		if (boundary)
		*boundary = final - 1 - (i_block & (ptrs - 1));