linux-kernel - Re: scsi: pm8001: fix double free in pm8001_pci

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Date:   Tue, 8 Aug 2017 15:10:01 +0200
From:   Jinpu Wang <jinpu.wang@...fitbricks.com>
To:     Pan Bian <bianpan2016@....com>
Cc:     lindar_liu <lindar_liu@...sh.com>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Linux SCSI Mailinglist <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: scsi: pm8001: fix double free in pm8001_pci_probe

On Tue, Aug 8, 2017 at 1:40 PM, Pan Bian <bianpan2016@....com> wrote:
> In function pm8001_pci_probe(), on errors that the control flow jumps to
> label err_out_ha_free, function pm8001_free() is called. In pm8001_free(),
> scsi_host_put() is called to release shost, which keeps the return value
> of scsi_host_alloc(). After pm8001_free() returns, kfree() is called to
> free shost again, resulting in a double free bug. This patch removes
> scsi_host_put() from pm8001_free() and explicitly calls scsi_host_put()
> to release Scsi_Host in need.
>
> Signed-off-by: Pan Bian <bianpan2016@....com>
Thanks Pan!

Looks good to me!

Reviewed-by: Jack Wang <jinpu.wang@...fitbricks.com>

> ---
>  drivers/scsi/pm8001/pm8001_init.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c
> index 034b2f7..2908881 100644
> --- a/drivers/scsi/pm8001/pm8001_init.c
> +++ b/drivers/scsi/pm8001/pm8001_init.c
> @@ -160,8 +160,6 @@ static void pm8001_free(struct pm8001_hba_info *pm8001_ha)
>                         }
>         }
>         PM8001_CHIP_DISP->chip_iounmap(pm8001_ha);
> -       if (pm8001_ha->shost)
> -               scsi_host_put(pm8001_ha->shost);
>         flush_workqueue(pm8001_wq);
>         kfree(pm8001_ha->tags);
>         kfree(pm8001_ha);
> @@ -1073,7 +1071,7 @@ static int pm8001_pci_probe(struct pci_dev *pdev,
>  err_out_free:
>         kfree(SHOST_TO_SAS_HA(shost));
>  err_out_free_host:
> -       kfree(shost);
> +       scsi_host_put(shost);
>  err_out_regions:
>         pci_release_regions(pdev);
>  err_out_disable:
> @@ -1112,6 +1110,7 @@ static void pm8001_pci_remove(struct pci_dev *pdev)
>                 for (j = 0; j < PM8001_MAX_MSIX_VEC; j++)
>                         tasklet_kill(&pm8001_ha->tasklet[j]);
>  #endif
> +       scsi_host_put(pm8001_ha->shost);
>         pm8001_free(pm8001_ha);
>         kfree(sha->sas_phy);
>         kfree(sha->sas_port);
> --
> 1.9.1
>
>



-- 
Jack Wang
Linux Kernel Developer

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