Re: scsi: BUG in scsi_init_io

Johannes Thumshirn
2017-01-31T09:21:10Z

On Tue, Jan 31, 2017 at 09:55:52AM +0100, Dmitry Vyukov wrote:
> Hello,
>
> The following program triggers BUG in scsi_init_io:

Well crashing a machine just because of an empty dma transfer is a bit harsh,
isn't it?

>From 86e6fa5f618fe588b98e923e032f33e075fcd4f4 Mon Sep 17 00:00:00 2001
From: Johannes Thumshirn <jthumshirn@suse.de>
Date: Tue, 31 Jan 2017 10:16:00 +0100
Subject: [PATCH] scsi: don't BUG_ON() empty DMA transfers

Don't crash the machine just because of an empty transfer. Use WARN_ON()
combined with returning an error.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
---
drivers/scsi/scsi_lib.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e9e1e14..414588a 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1040,7 +1040,8 @@ int scsi_init_io(struct scsi_cmnd *cmd)
bool is_mq = (rq->mq_ctx != NULL);
int error;

- BUG_ON(!blk_rq_nr_phys_segments(rq));
+ if (WARN_ON(!blk_rq_nr_phys_segments(rq)))
+ return -EINVAL;

error = scsi_init_sgtable(rq, &cmd->sdb);
if (error)
--
2.10.2

--
Johannes Thumshirn Storage
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