[PATCH v2 4/5] scsi: ufs: bsg: Reject UIC commands with a non-zero result byte

[Stanley Jhu <stanleyjhu@google.com>]

ufs_bsg_request() passes the user-supplied UIC argument2 unchanged,
including the result byte (bits 7:0) that only the host controller
writes. A non-zero value triggers the WARN_ON_ONCE() in
ufshcd_dispatch_uic_cmd() and corrupts the reported result. Found by
syzkaller.

Reject UIC commands that have the result byte set with -EINVAL.

Fixes: e77044c5a842 ("scsi: ufs-bsg: Add support for uic commands in ufs_bsg_request()")
Fixes: 9fb4c793223b ("scsi: ufs: core: Complain if UIC argument 2 is invalid")
Cc: stable@vger.kernel.org
Signed-off-by: Stanley Jhu <stanleyjhu@google.com>
---
Changes in v2:
- Reject a non-zero result byte with -EINVAL instead of clearing it,
  as suggested by Bart Van Assche. Dropped Peter's and Bean's
  Reviewed-by as the behavior changed.

 drivers/ufs/core/ufs_bsg.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/ufs/core/ufs_bsg.c b/drivers/ufs/core/ufs_bsg.c
index 0db830e54ef0..cadde515f040 100644
--- a/drivers/ufs/core/ufs_bsg.c
+++ b/drivers/ufs/core/ufs_bsg.c
@@ -179,6 +179,10 @@ static int ufs_bsg_request(struct bsg_job *job)
 		break;
 	case UPIU_TRANSACTION_UIC_CMD:
 		memcpy(&uc, &bsg_request->upiu_req.uc, UIC_CMD_SIZE);
+		if (uc.argument2 & MASK_UIC_COMMAND_RESULT) {
+			ret = -EINVAL;
+			break;
+		}
 		ret = ufshcd_send_bsg_uic_cmd(hba, &uc);
 		if (ret)
 			dev_err(hba->dev, "send uic cmd: error code %d\n", ret);
-- 
2.56.0.385.gd3acb90ef8-goog