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

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

[Johannes Thumshirn]

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>
---
 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 eb62772..4abb93a 100644
--- a/drivers/scsi/lpfc/lpfc_mbox.c
+++ b/drivers/scsi/lpfc/lpfc_mbox.c
@@ -2284,7 +2284,7 @@ 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);
@@ -2299,13 +2299,14 @@ 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);
 }
-- 
2.5.0

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

[Sebastian Herbszt]

Johannes Thumshirn wrote:
> 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.

A similar patch was posted by Colin Ian King on 2015-07-31 [1].

[1] http://marc.info/?l=linux-scsi&m=143835937206204&w=2

Sebastian

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

[Johannes Thumshirn]

Sebastian Herbszt <herbszt@gmx.de> writes:

> Johannes Thumshirn wrote:
>> 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.
>
> A similar patch was posted by Colin Ian King on 2015-07-31 [1].
>
> [1] http://marc.info/?l=linux-scsi&m=143835937206204&w=2

OK,

Is it already in James' tree (haven't checked)? The problematic code was
merged for 4.2-rc1 so if the fix (Collin's or mine I don't care) could go
in while we're still in the rc phase, we could avoid all that stable
circus.

Thanks for digging this out.

Byte,
        Johannes

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

[Sebastian Herbszt]

Johannes Thumshirn wrote:
> Sebastian Herbszt <herbszt@gmx.de> writes:
> 
> > Johannes Thumshirn wrote:
> >> 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.
> >
> > A similar patch was posted by Colin Ian King on 2015-07-31 [1].
> >
> > [1] http://marc.info/?l=linux-scsi&m=143835937206204&w=2
> 
> OK,
> 
> Is it already in James' tree (haven't checked)? The problematic code was
> merged for 4.2-rc1 so if the fix (Collin's or mine I don't care) could go
> in while we're still in the rc phase, we could avoid all that stable
> circus.
> 
> Thanks for digging this out.
> 
> Byte,
>         Johannes

It is not yet in scsi.git.

James S., Dick, which patch do you prefer?

Sebastian

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

[James Smart]

On 8/18/2015 6:27 PM, Sebastian Herbszt wrote:
> Johannes Thumshirn wrote:
>> Sebastian Herbszt <herbszt@gmx.de> writes:
>>
>>> Johannes Thumshirn wrote:
>>>> 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.
>>> A similar patch was posted by Colin Ian King on 2015-07-31 [1].
>>>
>>> [1] http://marc.info/?l=linux-scsi&m=143835937206204&w=2
>> OK,
>>
>> Is it already in James' tree (haven't checked)? The problematic code was
>> merged for 4.2-rc1 so if the fix (Collin's or mine I don't care) could go
>> in while we're still in the rc phase, we could avoid all that stable
>> circus.
>>
>> Thanks for digging this out.
>>
>> Byte,
>>          Johannes
> It is not yet in scsi.git.
>
> James S., Dick, which patch do you prefer?
>
> Sebastian

I looked at both and liked Johannes patch better.

-- james s