On Tue, 4 Apr 2023, James Bottomley wrote:
> > This reverts 3fe97ff3d9493 ("scsi: ses: Don't attach if enclosure has
> > no components") and introduces proper handling of case where there
> > are no detected secondary components, but primary component
> > (enumerated in num_enclosures) does exist. That fix was originally
> > proposed by Ding Hui <dinghui@xxxxxxxxxxxxxx>.
>
> I think everything in here looks fine except this:
>
> > --- a/drivers/scsi/ses.c
> > +++ b/drivers/scsi/ses.c
> > @@ -509,9 +509,6 @@ static int ses_enclosure_find_by_addr(struct
> > enclosure_device *edev,
> > int i;
> > struct ses_component *scomp;
> >
> > - if (!edev->component[0].scratch)
> > - return 0;
> > -
> > for (i = 0; i < edev->components; i++) {
> > scomp = edev->component[i].scratch;
> > if (scomp->addr != efd->addr)
>
> If you remove the check, then scomp could be NULL here and we'll oops
> on scomp->addr.
This hunk was taken from the original 2020 fix, but you are right, thanks
for spotting this.
Please find v2 below, with this hunk removed, and Tested-by: added.
From: Jiri Kosina <jkosina@xxxxxxx>
Subject: [PATCH] scsi: ses: Handle enclosure with just a primary component gracefully
This reverts 3fe97ff3d9493 ("scsi: ses: Don't attach if enclosure has no
components") and introduces proper handling of case where there are no detected
secondary components, but primary component (enumerated in num_enclosures)
does exist. That fix was originally proposed by Ding Hui <dinghui@xxxxxxxxxxxxxx>.
Completely ignoring devices that have one primary enclosure and no secondary one
results in ses_intf_add() bailing completely
scsi 2:0:0:254: enclosure has no enumerated components
scsi 2:0:0:254: Failed to bind enclosure -12ven in valid configurations such
even on valid configurations with 1 primary and 0 secondary enclosures as below:
# sg_ses /dev/sg0
3PARdata SES 3321
Supported diagnostic pages:
Supported Diagnostic Pages [sdp] [0x0]
Configuration (SES) [cf] [0x1]
Short Enclosure Status (SES) [ses] [0x8]
# sg_ses -p cf /dev/sg0
3PARdata SES 3321
Configuration diagnostic page:
number of secondary subenclosures: 0
generation code: 0x0
enclosure descriptor list
Subenclosure identifier: 0 [primary]
relative ES process id: 0, number of ES processes: 1
number of type descriptor headers: 1
enclosure logical identifier (hex): 20000002ac02068d
enclosure vendor: 3PARdata product: VV rev: 3321
type descriptor header and text list
Element type: Unspecified, subenclosure id: 0
number of possible elements: 1
The changelog for the original fix follows
=====
We can get a crash when disconnecting the iSCSI session,
the call trace like this:
[ffff00002a00fb70] kfree at ffff00000830e224
[ffff00002a00fba0] ses_intf_remove at ffff000001f200e4
[ffff00002a00fbd0] device_del at ffff0000086b6a98
[ffff00002a00fc50] device_unregister at ffff0000086b6d58
[ffff00002a00fc70] __scsi_remove_device at ffff00000870608c
[ffff00002a00fca0] scsi_remove_device at ffff000008706134
[ffff00002a00fcc0] __scsi_remove_target at ffff0000087062e4
[ffff00002a00fd10] scsi_remove_target at ffff0000087064c0
[ffff00002a00fd70] __iscsi_unbind_session at ffff000001c872c4
[ffff00002a00fdb0] process_one_work at ffff00000810f35c
[ffff00002a00fe00] worker_thread at ffff00000810f648
[ffff00002a00fe70] kthread at ffff000008116e98
In ses_intf_add, components count could be 0, and kcalloc 0 size scomp,
but not saved in edev->component[i].scratch
In this situation, edev->component[0].scratch is an invalid pointer,
when kfree it in ses_intf_remove_enclosure, a crash like above would happen
The call trace also could be other random cases when kfree cannot catch
the invalid pointer
We should not use edev->component[] array when the components count is 0
We also need check index when use edev->component[] array in
ses_enclosure_data_process
=====
Reported-by: Michal Kolar <mich.k@xxxxxxxxx>
Tested-by: Michal Kolar <mich.k@xxxxxxxxx>
Originally-by: Ding Hui <dinghui@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 3fe97ff3d9493 ("scsi: ses: Don't attach if enclosure has no components")
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
v1 -> v2:
- fix potential oops in ses_enclosure_find_by_addr() spotted by
James
- add Tested-by:
drivers/scsi/ses.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index b11a9162e73a..f3fa92f493ec 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -602,8 +602,10 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
components++,
type_ptr[0],
name);
- else
+ else if (components < edev->components)
ecomp = &edev->component[components++];
+ else
+ ecomp = ERR_PTR(-EINVAL);
if (!IS_ERR(ecomp)) {
if (addl_desc_ptr) {
@@ -734,11 +736,6 @@ static int ses_intf_add(struct device *cdev,
components += type_ptr[1];
}
- if (components == 0) {
- sdev_printk(KERN_WARNING, sdev, "enclosure has no enumerated components\n");
- goto err_free;
- }
-
ses_dev->page1 = buf;
ses_dev->page1_len = len;
buf = NULL;
@@ -780,9 +777,11 @@ static int ses_intf_add(struct device *cdev,
buf = NULL;
}
page2_not_supported:
- scomp = kcalloc(components, sizeof(struct ses_component), GFP_KERNEL);
- if (!scomp)
- goto err_free;
+ if (components > 0) {
+ scomp = kcalloc(components, sizeof(struct ses_component), GFP_KERNEL);
+ if (!scomp)
+ goto err_free;
+ }
edev = enclosure_register(cdev->parent, dev_name(&sdev->sdev_gendev),
components, &ses_enclosure_callbacks);
--
Jiri Kosina
SUSE Labs
