On Thu 21-06-07 03:33:43, Andreas Dilger wrote: > On Jun 20, 2007 14:56 +0200, Jan Kara wrote: > > when ext2fs_block_iterate() is called on a fast symlink (and I assume > > device inodes would be no different), then random things happen - the > > problem is ext2fs_block_iterate() just blindly takes portions of the inode > > and treats them as block numbers. Now I agree that garbage went in (it > > makes no sence to call this function on such inode) so garbage results but > > maybe it would be nicer to handle it more gracefully. Attached patch should > > do it. > > > --- a/lib/ext2fs/inode.c 2007-06-20 13:55:52.000000000 +0200 > > +++ b/lib/ext2fs/inode.c 2007-06-20 14:11:15.000000000 +0200 > > @@ -771,6 +771,10 @@ errcode_t ext2fs_get_blocks(ext2_filsys > > retval = ext2fs_read_inode(fs, ino, &inode); > > if (retval) > > return retval; > > + if (LINUX_S_ISCHR(inode.i_mode) || LINUX_S_ISBLK(inode.i_mode) || > > + (LINUX_S_ISLNK(inode.i_mode) && > > + ext2fs_inode_data_blocks(fs, &inode) == 0)) > > + return EXT2_ET_INVAL_INODE_TYPE; > > I would prefer that we NOT continue to make fast symlinks conditional upon > the i_blocks count. That causes problems if e.g. an EA block is present > (that would cause this blocks == 0 test to incorrectly fail), and may making > the check (blocks - !!i_file_acl) can still fail for other reasons where a > block is added to an inode (e.g. if we have larger EAs, etc). Note that ext2fs_inode_data_blocks() subtract number of EA blocks, so it is equivalent to (blocks - !!i_file_acl). The function is supposed to return the number of real data blocks so the test should be fine even in future. > I'd prefer to make this check "i_size < sizeof(i_block)" or similar, which > has always been true for fast symlinks, for every kernel that I have ever > seen. Personally I don't mind much. If Ted finds this better, I'll change that. Maybe introducing some macro LINUX_S_ISFASTLNK() would be fine. Honza -- Jan Kara <jack@xxxxxxx> SuSE CR Labs - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
