Re: 3.15-mw: Oops Workqueue: writeback bdi_writeback_workfn (flush-8:16) RIP: e030:[<ffffffff814c6bc1>] [<ffffffff814c6bc1>] kobject_put+0x11/0x70

From: Sander Eikelenboom
Date: Mon Apr 14 2014 - 09:06:31 EST



Monday, April 14, 2014, 1:30:15 PM, you wrote:

> On Sat, Apr 12, 2014 at 01:34:31PM +0200, Sander Eikelenboom wrote:
>> Hi,
>>
>> I just ran into the oops belowafter some uptime.

> Classic use after free introduced by my recent changes, sorry.

> This should fix it:

Thx !

> ---
> From: Christoph Hellwig <hch@xxxxxx>
> Subject: scsi: don't reference freed command in scsi_init_sgtable

> When scsi_init_io fails we have to release our device reference, but
> we do this trying to reference the just freed command. Add a local
> scsi_device pointer to fix this.

> Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>

> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 65a123d..54eff6a 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1044,6 +1044,7 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
> */
> int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
> {
> + struct scsi_device *sdev = cmd->device;
> struct request *rq = cmd->request;
>
> int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask);
> @@ -1091,7 +1092,7 @@ err_exit:
> scsi_release_buffers(cmd);
> cmd->request->special = NULL;
> scsi_put_command(cmd);
> - put_device(&cmd->device->sdev_gendev);
> + put_device(&sdev->sdev_gendev);
> return error;
> }
> EXPORT_SYMBOL(scsi_init_io);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/