Re: [PATCH 08/14] lpfc: Fix possible use-after-free and double free in lpfc_mbx_cmpl_rdp_page_a2()

[Hannes Reinecke <hare@suse.de>]

On 08/31/2015 10:48 PM, James Smart wrote:
> 
> From: Johannes Thumshirn <jthumshirn@suse.de>
> 
> If the bf_get() call in lpfc_mbx_cmpl_rdp_page_a2() does succeeds, execution
> continues normally and mp gets kfree()d.
> 
> If the subsequent call to lpfc_sli_issue_mbox() fails execution jumps to the
> error label where lpfc_mbuf_free() is called with mp->virt and mp->phys as
> function arguments. This is the use after free. Following the use after free mp
> gets kfree()d again which is a double free.
> 
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> Signed-off-by: James Smart <james.smart@avagotech.com>
> ---
>  drivers/scsi/lpfc/lpfc_mbox.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/lpfc/lpfc_mbox.c b/drivers/scsi/lpfc/lpfc_mbox.c
> index 723e110..18838ea 100644
> --- a/drivers/scsi/lpfc/lpfc_mbox.c
> +++ b/drivers/scsi/lpfc/lpfc_mbox.c
> @@ -2276,7 +2276,7 @@ lpfc_mbx_cmpl_rdp_page_a2(struct lpfc_hba *phba, LPFC_MBOXQ_t *mbox)
>  			(struct lpfc_rdp_context *)(mbox->context2);
>  
>  	if (bf_get(lpfc_mqe_status, &mbox->u.mqe))
> -		goto error;
> +		goto error_mbuf_free;
>  
>  	lpfc_sli_bemem_bcopy(mp->virt, &rdp_context->page_a2,
>  				DMP_SFF_PAGE_A2_SIZE);
> @@ -2291,13 +2291,14 @@ lpfc_mbx_cmpl_rdp_page_a2(struct lpfc_hba *phba, LPFC_MBOXQ_t *mbox)
>  	mbox->mbox_cmpl = lpfc_mbx_cmpl_rdp_link_stat;
>  	mbox->context2 = (struct lpfc_rdp_context *) rdp_context;
>  	if (lpfc_sli_issue_mbox(phba, mbox, MBX_NOWAIT) == MBX_NOT_FINISHED)
> -		goto error;
> +		goto error_cmd_free;
>  
>  	return;
>  
> -error:
> +error_mbuf_free:
>  	lpfc_mbuf_free(phba, mp->virt, mp->phys);
>  	kfree(mp);
> +error_cmd_free:
>  	lpfc_sli4_mbox_cmd_free(phba, mbox);
>  	rdp_context->cmpl(phba, rdp_context, FAILURE);
>  }
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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