[SCSI] BUG_ON() impossible condition in sg list counting

If blk_rq_map_sg wrote more than was allocated in the scatterlist,
BUG_ON() is probably the right thing to do.

[jejb: rejections fixed up]

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 3 insertions, 8 deletions

diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index 241815e911e7..93ece8f4e5de 100644
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -368,14 +368,9 @@ static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
         dprintk("cmd %p cnt %d %lu\n", cmd, scsi_sg_count(cmd),
                 rq_data_dir(rq));
         count = blk_rq_map_sg(rq->q, rq, scsi_sglist(cmd));
-        if (likely(count <= scsi_sg_count(cmd))) {
-                cmd->use_sg = count;
-                return 0;
-        }
-
-        eprintk("cmd %p cnt %d\n", cmd, scsi_sg_count(cmd));
-        scsi_free_sgtable(cmd);
-        return -EINVAL;
+        BUG_ON(count > cmd->use_sg);
+        cmd->use_sg = count;
+        return 0;
 }
 
 /* TODO: test this crap and replace bio_map_user with new interface maybe */