[PATCH 0/2] _scsih_sas_host_add early exits can crash system

[PATCH 0/2] _scsih_sas_host_add early exits can crash system

[Joe Lawrence]

There are many error paths in _scsih_sas_host_add that lead to an early
exit and a few that leave IOC resources uninitialized, setting the stage
for a later crash.

This can be emulated using a systemtap script like:

  % stap -g -e \
  'probe module("mpt3sas").function("mpt3sas_config_get_sas_iounit_pg0").return { $return = -1 }'

to force early exit, while remove/re-adding an MPT3 adapter:

  % lspci -D | grep MPT
  0000:54:00.0 Mass storage controller: LSI Logic / Symbios Logic SAS3008 PCI-Express Fusion-MPT SAS-3 (rev 02)

  % SYSFS=$(find /sys/devices -name 0000:54:00.0)
  % SYSFS_PARENT=$(dirname $SYSFS)

  % echo 1 > $SYSFS/remove
  % sleep 1m
  % echo 1 > $SYSFS_PARENT/rescan

These two patches fix:
  1) referencing unallocated ioc->sas_hba.phy[] space
  2) passing a NULL ioc->sas_hba.parent_dev to the scsi_transport_sas
     layer.

Note: these changes don't improve or retry adapter initialization, but
      only try to prevent the system from crashing

Joe Lawrence (2):
  mpt3sas - set num_phys after allocating phy[] space
  mpt3sas - avoid mpt3sas_transport_port_add NULL parent_dev

 drivers/scsi/mpt3sas/mpt3sas_scsih.c     | 20 +++++++++++---------
 drivers/scsi/mpt3sas/mpt3sas_transport.c |  5 +++++
 2 files changed, 16 insertions(+), 9 deletions(-)

-- 
1.8.3.1

[PATCH 1/2] mpt3sas - set num_phys after allocating phy[] space

[Joe Lawrence]

In _scsih_sas_host_add, the number of HBA phys are determined and then
later used to allocate an array of struct  _sas_phy's.  If the routine
sets ioc->sas_hba.num_phys, but then fails to allocate the
ioc->sas_hba.phy array (by kcalloc error or other intermediate
error/exit path), ioc->sas_hba is left in a dangerous state: all readers
of ioc->sas_hba.phy[] do so by indexing it from 0..ioc->sas_hba.num_phys
without checking that the space was ever allocated.

Modify _scsih_sas_host_add to set ioc->sas_hba.num_phys only after
successfully allocating ioc->sas_hba.phy[].

Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
---
 drivers/scsi/mpt3sas/mpt3sas_scsih.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index f2139e5604a3..6e36d20c9e0b 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -4893,13 +4893,22 @@ _scsih_sas_host_add(struct MPT3SAS_ADAPTER *ioc)
 	u16 ioc_status;
 	u16 sz;
 	u8 device_missing_delay;
+	u8 num_phys;
 
-	mpt3sas_config_get_number_hba_phys(ioc, &ioc->sas_hba.num_phys);
-	if (!ioc->sas_hba.num_phys) {
+	mpt3sas_config_get_number_hba_phys(ioc, &num_phys);
+	if (!num_phys) {
 		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
 		    ioc->name, __FILE__, __LINE__, __func__);
 		return;
 	}
+	ioc->sas_hba.phy = kcalloc(num_phys,
+	    sizeof(struct _sas_phy), GFP_KERNEL);
+	if (!ioc->sas_hba.phy) {
+		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
+		    ioc->name, __FILE__, __LINE__, __func__);
+		goto out;
+	}
+	ioc->sas_hba.num_phys = num_phys;
 
 	/* sas_iounit page 0 */
 	sz = offsetof(Mpi2SasIOUnitPage0_t, PhyData) + (ioc->sas_hba.num_phys *
@@ -4959,13 +4968,6 @@ _scsih_sas_host_add(struct MPT3SAS_ADAPTER *ioc)
 		    MPI2_SASIOUNIT1_REPORT_MISSING_TIMEOUT_MASK;
 
 	ioc->sas_hba.parent_dev = &ioc->shost->shost_gendev;
-	ioc->sas_hba.phy = kcalloc(ioc->sas_hba.num_phys,
-	    sizeof(struct _sas_phy), GFP_KERNEL);
-	if (!ioc->sas_hba.phy) {
-		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
-		    ioc->name, __FILE__, __LINE__, __func__);
-		goto out;
-	}
 	for (i = 0; i < ioc->sas_hba.num_phys ; i++) {
 		if ((mpt3sas_config_get_phy_pg0(ioc, &mpi_reply, &phy_pg0,
 		    i))) {
-- 
1.8.3.1

[PATCH 2/2] mpt3sas - avoid mpt3sas_transport_port_add NULL parent_dev

[Joe Lawrence]

If _scsih_sas_host_add's call to mpt3sas_config_get_sas_iounit_pg0
fails, ioc->sas_hba.parent_dev may be left uninitialized.  A later
device probe could invoke mpt3sas_transport_port_add which will call
sas_port_alloc_num [scsi_transport_sas] with a NULL parent_dev pointer.

Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
---
 drivers/scsi/mpt3sas/mpt3sas_transport.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_transport.c b/drivers/scsi/mpt3sas/mpt3sas_transport.c
index 6a84b82d71bb..ff93286bc32f 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_transport.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_transport.c
@@ -705,6 +705,11 @@ mpt3sas_transport_port_add(struct MPT3SAS_ADAPTER *ioc, u16 handle,
 		goto out_fail;
 	}
 
+	if (!sas_node->parent_dev) {
+		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
+		    ioc->name, __FILE__, __LINE__, __func__);
+		goto out_fail;
+	}
 	port = sas_port_alloc_num(sas_node->parent_dev);
 	if ((sas_port_add(port))) {
 		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
-- 
1.8.3.1

Re: [PATCH 1/2] mpt3sas - set num_phys after allocating phy[] space

[Sreekanth Reddy]

Hi,

This patch looks good. Please consider this patch as Ack-by: Sreekanth Reddy
<sreekanth.reddy@broadcom.com>

Thanks,
Sreekanth

On Thu, May 26, 2016 at 12:44 AM, Joe Lawrence <joe.lawrence@stratus.com> wrote:
> In _scsih_sas_host_add, the number of HBA phys are determined and then
> later used to allocate an array of struct  _sas_phy's.  If the routine
> sets ioc->sas_hba.num_phys, but then fails to allocate the
> ioc->sas_hba.phy array (by kcalloc error or other intermediate
> error/exit path), ioc->sas_hba is left in a dangerous state: all readers
> of ioc->sas_hba.phy[] do so by indexing it from 0..ioc->sas_hba.num_phys
> without checking that the space was ever allocated.
>
> Modify _scsih_sas_host_add to set ioc->sas_hba.num_phys only after
> successfully allocating ioc->sas_hba.phy[].
>
> Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
> ---
>  drivers/scsi/mpt3sas/mpt3sas_scsih.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> index f2139e5604a3..6e36d20c9e0b 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> @@ -4893,13 +4893,22 @@ _scsih_sas_host_add(struct MPT3SAS_ADAPTER *ioc)
>         u16 ioc_status;
>         u16 sz;
>         u8 device_missing_delay;
> +       u8 num_phys;
>
> -       mpt3sas_config_get_number_hba_phys(ioc, &ioc->sas_hba.num_phys);
> -       if (!ioc->sas_hba.num_phys) {
> +       mpt3sas_config_get_number_hba_phys(ioc, &num_phys);
> +       if (!num_phys) {
>                 pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
>                     ioc->name, __FILE__, __LINE__, __func__);
>                 return;
>         }
> +       ioc->sas_hba.phy = kcalloc(num_phys,
> +           sizeof(struct _sas_phy), GFP_KERNEL);
> +       if (!ioc->sas_hba.phy) {
> +               pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
> +                   ioc->name, __FILE__, __LINE__, __func__);
> +               goto out;
> +       }
> +       ioc->sas_hba.num_phys = num_phys;
>
>         /* sas_iounit page 0 */
>         sz = offsetof(Mpi2SasIOUnitPage0_t, PhyData) + (ioc->sas_hba.num_phys *
> @@ -4959,13 +4968,6 @@ _scsih_sas_host_add(struct MPT3SAS_ADAPTER *ioc)
>                     MPI2_SASIOUNIT1_REPORT_MISSING_TIMEOUT_MASK;
>
>         ioc->sas_hba.parent_dev = &ioc->shost->shost_gendev;
> -       ioc->sas_hba.phy = kcalloc(ioc->sas_hba.num_phys,
> -           sizeof(struct _sas_phy), GFP_KERNEL);
> -       if (!ioc->sas_hba.phy) {
> -               pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
> -                   ioc->name, __FILE__, __LINE__, __func__);
> -               goto out;
> -       }
>         for (i = 0; i < ioc->sas_hba.num_phys ; i++) {
>                 if ((mpt3sas_config_get_phy_pg0(ioc, &mpi_reply, &phy_pg0,
>                     i))) {
> --
> 1.8.3.1
>
> --
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Re: [PATCH 2/2] mpt3sas - avoid mpt3sas_transport_port_add NULL parent_dev

[Sreekanth Reddy]

Hi,

This patch looks good. Please consider this patch as Ack-by: Sreekanth Reddy
<sreekanth.reddy@broadcom.com>

Thanks,
Sreekanth


On Thu, May 26, 2016 at 12:44 AM, Joe Lawrence <joe.lawrence@stratus.com> wrote:
> If _scsih_sas_host_add's call to mpt3sas_config_get_sas_iounit_pg0
> fails, ioc->sas_hba.parent_dev may be left uninitialized.  A later
> device probe could invoke mpt3sas_transport_port_add which will call
> sas_port_alloc_num [scsi_transport_sas] with a NULL parent_dev pointer.
>
> Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
> ---
>  drivers/scsi/mpt3sas/mpt3sas_transport.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_transport.c b/drivers/scsi/mpt3sas/mpt3sas_transport.c
> index 6a84b82d71bb..ff93286bc32f 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_transport.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_transport.c
> @@ -705,6 +705,11 @@ mpt3sas_transport_port_add(struct MPT3SAS_ADAPTER *ioc, u16 handle,
>                 goto out_fail;
>         }
>
> +       if (!sas_node->parent_dev) {
> +               pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
> +                   ioc->name, __FILE__, __LINE__, __func__);
> +               goto out_fail;
> +       }
>         port = sas_port_alloc_num(sas_node->parent_dev);
>         if ((sas_port_add(port))) {
>                 pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
> --
> 1.8.3.1
>
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Re: [PATCH 0/2] _scsih_sas_host_add early exits can crash system

[Martin K. Petersen]

>>>>> "Joe" == Joe Lawrence <joe.lawrence@stratus.com> writes:

Joe> There are many error paths in _scsih_sas_host_add that lead to an
Joe> early exit and a few that leave IOC resources uninitialized,
Joe> setting the stage for a later crash.

Applied to 4.8/scsi-queue.

Please make sure to use "mpt3sas: foo bar" in the patch
descriptions. You had used "mpt3sas - foo bar".

Thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering