[PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe

[PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe

[Letu Ren]

In __qedf_probe, if `qedf->cdev` is NULL which means
qed_ops->common->probe() failed, then the program will goto label err1,
scsi_host_put() will free `lport->host` pointer. Because the memory `qedf`
points to is allocated by libfc_host_alloc(), it will be freed by
scsi_host_put(). However, the if statement below label err0 only checks
whether qedf is NULL but doesn't check whether the memory has been freed.
So a UAF bug occurred.

There are two ways to get to the statements below err0. the first one is
described as before. `qedf` should be set to NULL. The second way is goto
`err0` directly. In this way `qedf` hasn't been changed and it has the
initial value `NULL`. So the program wont't go to the if statement in any
situation.

The KASAN logs are as follows:

[    2.312969] BUG: KASAN: use-after-free in __qedf_probe+0x5dcf/0x6bc0
[    2.312969]
[    2.312969] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
[    2.312969] Call Trace:
[    2.312969]  dump_stack_lvl+0x59/0x7b
[    2.312969]  print_address_description+0x7c/0x3b0
[    2.312969]  ? __qedf_probe+0x5dcf/0x6bc0
[    2.312969]  __kasan_report+0x160/0x1c0
[    2.312969]  ? __qedf_probe+0x5dcf/0x6bc0
[    2.312969]  kasan_report+0x4b/0x70
[    2.312969]  ? kobject_put+0x25d/0x290
[    2.312969]  kasan_check_range+0x2ca/0x310
[    2.312969]  __qedf_probe+0x5dcf/0x6bc0
[    2.312969]  ? selinux_kernfs_init_security+0xdc/0x5f0
[    2.312969]  ? trace_rpm_return_int_rcuidle+0x18/0x120
[    2.312969]  ? rpm_resume+0xa5c/0x16e0
[    2.312969]  ? qedf_get_generic_tlv_data+0x160/0x160
[    2.312969]  local_pci_probe+0x13c/0x1f0
[    2.312969]  pci_device_probe+0x37e/0x6c0

Reported-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Letu Ren <fantasquex@gmail.com>
Co-developed-by: Wende Tan <twd2.me@gmail.com>
Signed-off-by: Wende Tan <twd2.me@gmail.com>
---
 drivers/scsi/qedf/qedf_main.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
index 42d0d941dba5..3ea552acd82a 100644
--- a/drivers/scsi/qedf/qedf_main.c
+++ b/drivers/scsi/qedf/qedf_main.c
@@ -3683,11 +3683,6 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
 err1:
 	scsi_host_put(lport->host);
 err0:
-	if (qedf) {
-		QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_DISC, "Probe done.\n");
-
-		clear_bit(QEDF_PROBING, &qedf->flags);
-	}
 	return rc;
 }
 
-- 
2.33.1

RE: [EXT] [PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe

[Saurav Kashyap]

Hi Letu Ren,

> -----Original Message-----
> From: Letu Ren <fantasquex@gmail.com>
> Sent: Friday, November 12, 2021 5:37 PM
> To: Saurav Kashyap <skashyap@marvell.com>; Javed Hasan
> <jhasan@marvell.com>; jejb@linux.ibm.com; martin.petersen@oracle.com
> Cc: GR-QLogic-Storage-Upstream <GR-QLogic-Storage-
> Upstream@marvell.com>; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; Letu Ren <fantasquex@gmail.com>; Zheyu Ma
> <zheyuma97@gmail.com>; Wende Tan <twd2.me@gmail.com>
> Subject: [EXT] [PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe
> 
> External Email
> 
> ----------------------------------------------------------------------
> In __qedf_probe, if `qedf->cdev` is NULL which means
> qed_ops->common->probe() failed, then the program will goto label err1,
> scsi_host_put() will free `lport->host` pointer. Because the memory `qedf`
> points to is allocated by libfc_host_alloc(), it will be freed by
> scsi_host_put(). However, the if statement below label err0 only checks
> whether qedf is NULL but doesn't check whether the memory has been freed.
> So a UAF bug occurred.
> 
> There are two ways to get to the statements below err0. the first one is
> described as before. `qedf` should be set to NULL. The second way is goto
> `err0` directly. In this way `qedf` hasn't been changed and it has the
> initial value `NULL`. So the program wont't go to the if statement in any
> situation.
> 
> The KASAN logs are as follows:
> 
> [    2.312969] BUG: KASAN: use-after-free in __qedf_probe+0x5dcf/0x6bc0
> [    2.312969]
> [    2.312969] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> [    2.312969] Call Trace:
> [    2.312969]  dump_stack_lvl+0x59/0x7b
> [    2.312969]  print_address_description+0x7c/0x3b0
> [    2.312969]  ? __qedf_probe+0x5dcf/0x6bc0
> [    2.312969]  __kasan_report+0x160/0x1c0
> [    2.312969]  ? __qedf_probe+0x5dcf/0x6bc0
> [    2.312969]  kasan_report+0x4b/0x70
> [    2.312969]  ? kobject_put+0x25d/0x290
> [    2.312969]  kasan_check_range+0x2ca/0x310
> [    2.312969]  __qedf_probe+0x5dcf/0x6bc0
> [    2.312969]  ? selinux_kernfs_init_security+0xdc/0x5f0
> [    2.312969]  ? trace_rpm_return_int_rcuidle+0x18/0x120
> [    2.312969]  ? rpm_resume+0xa5c/0x16e0
> [    2.312969]  ? qedf_get_generic_tlv_data+0x160/0x160
> [    2.312969]  local_pci_probe+0x13c/0x1f0
> [    2.312969]  pci_device_probe+0x37e/0x6c0
> 
> Reported-by: Zheyu Ma <zheyuma97@gmail.com>
> Signed-off-by: Letu Ren <fantasquex@gmail.com>
> Co-developed-by: Wende Tan <twd2.me@gmail.com>
> Signed-off-by: Wende Tan <twd2.me@gmail.com>
> ---
>  drivers/scsi/qedf/qedf_main.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
> index 42d0d941dba5..3ea552acd82a 100644
> --- a/drivers/scsi/qedf/qedf_main.c
> +++ b/drivers/scsi/qedf/qedf_main.c
> @@ -3683,11 +3683,6 @@ static int __qedf_probe(struct pci_dev *pdev, int
> mode)
>  err1:
>  	scsi_host_put(lport->host);
>  err0:
> -	if (qedf) {
> -		QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_DISC, "Probe
> done.\n");
> -
> -		clear_bit(QEDF_PROBING, &qedf->flags);
> -	}
>  	return rc;
>  }

Thanks for the patch.

Acked-by: Saurav Kashyap <skashyap@marvell.com>

Thanks,
~Saurav
> 
> --
> 2.33.1

Re: [EXT] [PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe

[Letu Ren]

Hi Saurav,

> Thanks for the patch.
>
> Acked-by: Saurav Kashyap <skashyap@marvell.com>


This is a friendly reminder. I wonder the review progress of this
patch. Almost a year has passed since I submitted the patch. And we
have tested qedf on Linux 6.0-rc0. This UAF problem still exists. If
there's anything I can do to help with this issue please let me know.
I'm willing to help.

Letu Ren

RE: [EXT] [PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe

[Saurav Kashyap]

Hi Letu Ren,
I have already ack-ed this patch, so nothing to be done from my side.

Hi Martin,
I have ack-ed this patch, kindly pull it.

Thanks,
~saurav

> -----Original Message-----
> From: Letu Ren <fantasquex@gmail.com>
> Sent: Tuesday, September 6, 2022 3:31 PM
> To: Saurav Kashyap <skashyap@marvell.com>
> Cc: Javed Hasan <jhasan@marvell.com>; jejb@linux.ibm.com;
> martin.petersen@oracle.com; GR-QLogic-Storage-Upstream <GR-QLogic-
> Storage-Upstream@marvell.com>; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; Zheyu Ma <zheyuma97@gmail.com>; Wende Tan
> <twd2.me@gmail.com>
> Subject: Re: [EXT] [PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe
> 
> Hi Saurav,
> 
> > Thanks for the patch.
> >
> > Acked-by: Saurav Kashyap <skashyap@marvell.com>
> 
> 
> This is a friendly reminder. I wonder the review progress of this
> patch. Almost a year has passed since I submitted the patch. And we
> have tested qedf on Linux 6.0-rc0. This UAF problem still exists. If
> there's anything I can do to help with this issue please let me know.
> I'm willing to help.
> 
> Letu Ren

Re: [PATCH] scsi: qedf: Fix a UAF bug in __qedf_probe

[Martin K. Petersen]

On Fri, 12 Nov 2021 20:06:41 +0800, Letu Ren wrote:

> In __qedf_probe, if `qedf->cdev` is NULL which means
> qed_ops->common->probe() failed, then the program will goto label err1,
> scsi_host_put() will free `lport->host` pointer. Because the memory `qedf`
> points to is allocated by libfc_host_alloc(), it will be freed by
> scsi_host_put(). However, the if statement below label err0 only checks
> whether qedf is NULL but doesn't check whether the memory has been freed.
> So a UAF bug occurred.
> 
> [...]

Applied to 6.0/scsi-fixes, thanks!

[1/1] scsi: qedf: Fix a UAF bug in __qedf_probe
      https://git.kernel.org/mkp/scsi/c/fbfe96869b78

-- 
Martin K. Petersen	Oracle Linux Engineering