scsi: st: Don't modify unknown block number in MTIOCGET

Struct mtget field mt_blkno -1 means it is unknown. Don't add anything to
it.

Signed-off-by: Kai Mäkisara <Kai.Makisara@kolumbus.fi>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219419#c14
Link: https://lore.kernel.org/r/20241106095723.63254-2-Kai.Makisara@kolumbus.fi
Reviewed-by: John Meneghini <jmeneghi@redhat.com>
Tested-by: John Meneghini <jmeneghi@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index d50bad3..9f480a1 100644 (file)
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -3756,7 +3756,7 @@ static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
                    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
                mt_status.mt_blkno = STps->drv_block;
                mt_status.mt_fileno = STps->drv_file;
-               if (STp->block_size != 0) {
+               if (STp->block_size != 0 && mt_status.mt_blkno >= 0) {
                        if (STps->rw == ST_WRITING)
                                mt_status.mt_blkno +=
                                    (STp->buffer)->buffer_bytes / STp->block_size;