[PATCH AUTOSEL 4.19 4/6] scsi: st: Don't modify unknown block number in MTIOCGET

[Sasha Levin]

From: Kai Mäkisara <Kai.Makisara@xxxxxxxxxxx>

[ Upstream commit 5bb2d6179d1a8039236237e1e94cfbda3be1ed9e ]

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

Signed-off-by: Kai Mäkisara <Kai.Makisara@xxxxxxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219419#c14
Link: https://lore.kernel.org/r/20241106095723.63254-2-Kai.Makisara@xxxxxxxxxxx
Reviewed-by: John Meneghini <jmeneghi@xxxxxxxxxx>
Tested-by: John Meneghini <jmeneghi@xxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/scsi/st.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 5078db7743cd0..c6b341415a125 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -3752,7 +3752,7 @@ 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;
-- 
2.43.0