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Subject[17/90] ext4: Fix wrong comparisons in mext_check_arguments()
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
(cherry picked from commit 70d5d3dcea47c16058d2b093c29e07fdf61b56ad)

The mext_check_arguments() function in move_extents.c has wrong
comparisons. orig_start which is passed from user-space is block
unit, but i_size of inode is byte unit, therefore the checks do not
work fine. This mis-check leads to the overflow of 'len' and then
hits BUG_ON() in ext4_move_extents(). The patch fixes this issue.

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Reviewed-by: Greg Freemyer <greg.freemyer@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/ext4/move_extent.c | 46 +++++++++++++++++++++++++++-------------------
1 file changed, 27 insertions(+), 19 deletions(-)

--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -898,6 +898,10 @@ mext_check_arguments(struct inode *orig_
struct inode *donor_inode, __u64 orig_start,
__u64 donor_start, __u64 *len, __u64 moved_len)
{
+ ext4_lblk_t orig_blocks, donor_blocks;
+ unsigned int blkbits = orig_inode->i_blkbits;
+ unsigned int blocksize = 1 << blkbits;
+
/* Regular file check */
if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
ext4_debug("ext4 move extent: The argument files should be "
@@ -972,43 +976,47 @@ mext_check_arguments(struct inode *orig_
}

if (orig_inode->i_size > donor_inode->i_size) {
- if (orig_start >= donor_inode->i_size) {
+ donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
+ /* TODO: eliminate this artificial restriction */
+ if (orig_start >= donor_blocks) {
ext4_debug("ext4 move extent: orig start offset "
- "[%llu] should be less than donor file size "
- "[%lld] [ino:orig %lu, donor_inode %lu]\n",
- orig_start, donor_inode->i_size,
+ "[%llu] should be less than donor file blocks "
+ "[%u] [ino:orig %lu, donor %lu]\n",
+ orig_start, donor_blocks,
orig_inode->i_ino, donor_inode->i_ino);
return -EINVAL;
}

- if (orig_start + *len > donor_inode->i_size) {
+ /* TODO: eliminate this artificial restriction */
+ if (orig_start + *len > donor_blocks) {
ext4_debug("ext4 move extent: End offset [%llu] should "
- "be less than donor file size [%lld]."
- "So adjust length from %llu to %lld "
+ "be less than donor file blocks [%u]."
+ "So adjust length from %llu to %llu "
"[ino:orig %lu, donor %lu]\n",
- orig_start + *len, donor_inode->i_size,
- *len, donor_inode->i_size - orig_start,
+ orig_start + *len, donor_blocks,
+ *len, donor_blocks - orig_start,
orig_inode->i_ino, donor_inode->i_ino);
- *len = donor_inode->i_size - orig_start;
+ *len = donor_blocks - orig_start;
}
} else {
- if (orig_start >= orig_inode->i_size) {
+ orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
+ if (orig_start >= orig_blocks) {
ext4_debug("ext4 move extent: start offset [%llu] "
- "should be less than original file size "
- "[%lld] [inode:orig %lu, donor %lu]\n",
- orig_start, orig_inode->i_size,
+ "should be less than original file blocks "
+ "[%u] [ino:orig %lu, donor %lu]\n",
+ orig_start, orig_blocks,
orig_inode->i_ino, donor_inode->i_ino);
return -EINVAL;
}

- if (orig_start + *len > orig_inode->i_size) {
+ if (orig_start + *len > orig_blocks) {
ext4_debug("ext4 move extent: Adjust length "
- "from %llu to %lld. Because it should be "
- "less than original file size "
+ "from %llu to %llu. Because it should be "
+ "less than original file blocks "
"[ino:orig %lu, donor %lu]\n",
- *len, orig_inode->i_size - orig_start,
+ *len, orig_blocks - orig_start,
orig_inode->i_ino, donor_inode->i_ino);
- *len = orig_inode->i_size - orig_start;
+ *len = orig_blocks - orig_start;
}
}




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