From: Damien Le Moal damien.lemoal@opensource.wdc.com
commit a608da3bd730d718f2d3ebec1c26f9865f8f17ce upstream.
Using REQ_OP_ZONE_APPEND operations for synchronous writes to sequential files succeeds regardless of the zone write pointer position, as long as the target zone is not full. This means that if an external (buggy) application writes to the zone of a sequential file underneath the file system, subsequent file write() operation will succeed but the file size will not be correct and the file will contain invalid data written by another application.
Modify zonefs_file_dio_append() to check the written sector of an append write (returned in bio->bi_iter.bi_sector) and return -EIO if there is a mismatch with the file zone wp offset field. This change triggers a call to zonefs_io_error() and a zone check. Modify zonefs_io_error_cb() to not expose the unexpected data after the current inode size when the errors=remount-ro mode is used. Other error modes are correctly handled already.
Fixes: 02ef12a663c7 ("zonefs: use REQ_OP_ZONE_APPEND for sync DIO") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal damien.lemoal@opensource.wdc.com Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/zonefs/super.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
--- a/fs/zonefs/super.c +++ b/fs/zonefs/super.c @@ -402,6 +402,10 @@ static int zonefs_io_error_cb(struct blk data_size = zonefs_check_zone_condition(inode, zone, false, false); } + } else if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_RO && + data_size > isize) { + /* Do not expose garbage data */ + data_size = isize; }
/* @@ -765,6 +769,24 @@ static ssize_t zonefs_file_dio_append(st
ret = submit_bio_wait(bio);
+ /* + * If the file zone was written underneath the file system, the zone + * write pointer may not be where we expect it to be, but the zone + * append write can still succeed. So check manually that we wrote where + * we intended to, that is, at zi->i_wpoffset. + */ + if (!ret) { + sector_t wpsector = + zi->i_zsector + (zi->i_wpoffset >> SECTOR_SHIFT); + + if (bio->bi_iter.bi_sector != wpsector) { + zonefs_warn(inode->i_sb, + "Corrupted write pointer %llu for zone at %llu\n", + wpsector, zi->i_zsector); + ret = -EIO; + } + } + zonefs_file_write_dio_end_io(iocb, size, ret, 0); trace_zonefs_file_dio_append(inode, size, ret);