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From: Greg KH on 30 Jul 2010 13:30
2.6.32-stable review patch. If anyone has any objections, please let us know.

------------------

commit f70f362b4a6fe47c239dbfb3efc0cc2c10e4f09c upstream (as of v2.6.34-git13)

If the EOFBLOCK_FL flag is set when it should not be and the inode is
zero length, then eh_entries is zero, and ex is NULL, so dereferencing
ex to print ex->ee_block causes a kernel OOPS in
ext4_ext_map_blocks().

On top of that, the error message which is printed isn't very helpful.
So we fix this by printing something more explanatory which doesn't
involve trying to print ex->ee_block.

Addresses-Google-Bug: #2655740

Signed-off-by: "Theodore Ts'o" <tytso(a)mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
---
fs/ext4/extents.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3281,8 +3281,8 @@ int ext4_ext_get_blocks(handle_t *handle
*/
if (path[depth].p_ext == NULL && depth != 0) {
ext4_error(inode->i_sb, __func__, "bad extent address "
- "inode: %lu, iblock: %d, depth: %d",
- inode->i_ino, iblock, depth);
+ "inode: %lu, iblock: %lu, depth: %d",
+ inode->i_ino, (unsigned long) iblock, depth);
err = -EIO;
goto out2;
}
@@ -3418,8 +3418,11 @@ int ext4_ext_get_blocks(handle_t *handle
} else {
WARN_ON(eh->eh_entries == 0);
ext4_error(inode->i_sb, __func__,
- "inode#%lu, eh->eh_entries = 0!", inode->i_ino);
- }
+ "inode#%lu, eh->eh_entries = 0 and "
+ "EOFBLOCKS_FL set", inode->i_ino);
+ err = -EIO;
+ goto out2;
+ }
}
err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
if (err) {


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