Re: [PATCH] scsi: avoid use of reclaimed reference

From: Bart Van Assche
Date: Wed Nov 13 2013 - 07:36:04 EST


On 11/13/13 02:10, David Decotigny wrote:
This patch avoids to use an object after it was potentially reclaimed
by scsi_device_put().

Signed-off-by: David Decotigny <decot@xxxxxxxxxxxx>
---
drivers/scsi/scsi_scan.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 307a811..16e4a44 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1498,12 +1498,14 @@ static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
out_err:
kfree(lun_data);
out:
- scsi_device_put(sdev);
- if (scsi_device_created(sdev))
+ if (scsi_device_created(sdev)) {
/*
* the sdev we used didn't appear in the report luns scan
*/
__scsi_remove_device(sdev);
+ }
+
+ scsi_device_put(sdev);
return ret;
}

It would help if you could explain why you started looking at this code. Is the above patch something you came up with after having analyzed the SCSI mid-layer source code or perhaps as the result of a test that failed ? If so, which test was it that failed ?

Thanks,

Bart.

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