Re: [PATCH] scsi: ses: Fix crash caused by kfree an invalid pointer
From: Douglas Gilbert
Date: Sun Nov 29 2020 - 00:14:51 EST
On 2020-11-28 6:27 p.m., James Bottomley wrote:
On Sat, 2020-11-28 at 20:23 +0800, Ding Hui wrote:
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
Tested-by: Zeng Zhicong <timmyzeng@xxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx> # 2.6.25+
Signed-off-by: Ding Hui <dinghui@xxxxxxxxxxxxxx>
This doesn't really look to be the right thing to do: an enclosure
which has no component can't usefully be controlled by the driver since
there's nothing for it to do, so what we should do in this situation is
refuse to attach like the proposed patch below.
It does seem a bit odd that someone would build an enclosure that
doesn't enclose anything, so would you mind running
sg_ses -e
'-e' is the short form of '--enumerate'. That will report the names
and abbreviations of the diagnostic pages that the utility itself
knows about (and supports). It won't show anything specific about
the environment that sg_ses is executed in.
You probably meant:
sg_ses <ses_device>
Examples of the likely forms are:
sg_ses /dev/bsg/1:0:0:0
sg_ses /dev/sg2
sg_ses /dev/ses0
This from a nearby machine:
$ lsscsi -gs
[3:0:0:0] disk ATA Samsung SSD 850 1B6Q /dev/sda /dev/sg0 120GB
[4:0:0:0] disk IBM-207x HUSMM8020ASS20 J4B6 /dev/sdc /dev/sg2 200GB
[4:0:1:0] disk ATA INTEL SSDSC2KW25 003C /dev/sdd /dev/sg3 256GB
[4:0:2:0] disk SEAGATE ST10000NM0096 E005 /dev/sde /dev/sg4 10.0TB
[4:0:3:0] enclosu Areca Te ARC-802801.37.69 0137 - /dev/sg5 -
[4:0:4:0] enclosu Intel RES2SV240 0d00 - /dev/sg6 -
[7:0:0:0] disk Kingston DataTravelerMini PMAP /dev/sdb /dev/sg1 1.03GB
[N:0:0:1] disk WDC WDS256G1X0C-00ENX0__1 /dev/nvme0n1 - 256GB
# sg_ses /dev/sg5
Areca Te ARC-802801.37.69 0137
Supported diagnostic pages:
Supported Diagnostic Pages [sdp] [0x0]
Configuration (SES) [cf] [0x1]
Enclosure Status/Control (SES) [ec,es] [0x2]
String In/Out (SES) [str] [0x4]
Threshold In/Out (SES) [th] [0x5]
Element Descriptor (SES) [ed] [0x7]
Additional Element Status (SES-2) [aes] [0xa]
Supported SES Diagnostic Pages (SES-2) [ssp] [0xd]
Download Microcode (SES-2) [dm] [0xe]
Subenclosure Nickname (SES-2) [snic] [0xf]
Protocol Specific (SAS transport) [] [0x3f]
# sg_ses -p cf /dev/sg5
Areca Te ARC-802801.37.69 0137
Configuration diagnostic page:
number of secondary subenclosures: 0
generation code: 0x0
enclosure descriptor list
Subenclosure identifier: 0 [primary]
relative ES process id: 1, number of ES processes: 1
number of type descriptor headers: 9
enclosure logical identifier (hex): d5b401503fc0ec16
enclosure vendor: Areca Te product: ARC-802801.37.69 rev: 0137
vendor-specific data:
11 22 33 44 55 00 00 00 ."3DU...
type descriptor header and text list
Element type: Array device slot, subenclosure id: 0
number of possible elements: 24
text: ArrayDevicesInSubEnclsr0
Element type: Enclosure, subenclosure id: 0
number of possible elements: 1
text: EnclosureElementInSubEnclsr0
Element type: SAS expander, subenclosure id: 0
number of possible elements: 1
text: SAS Expander
Element type: Cooling, subenclosure id: 0
number of possible elements: 5
text: CoolingElementInSubEnclsr0
Element type: Temperature sensor, subenclosure id: 0
number of possible elements: 2
text: TempSensorsInSubEnclsr0
Element type: Voltage sensor, subenclosure id: 0
number of possible elements: 2
text: VoltageSensorsInSubEnclsr0
Element type: SAS connector, subenclosure id: 0
number of possible elements: 3
text: ConnectorsInSubEnclsr0
Element type: Power supply, subenclosure id: 0
number of possible elements: 2
text: PowerSupplyInSubEnclsr0
Element type: Audible alarm, subenclosure id: 0
number of possible elements: 1
text: AudibleAlarmInSubEnclsr0
Doug Gilbert
on it and reporting back what it shows? It's possible there's another
type that the enclosure device should be tracking.
Regards,
James
---8>8>8><8<8<8--------
From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Subject: [PATCH] scsi: ses: don't attach if enclosure has no components
An enclosure with no components can't usefully be operated by the
driver (since effectively it has nothing to manage), so report the
problem and don't attach. Not attaching also fixes an oops which
could occur if the driver tries to manage a zero component enclosure.
Reported-by: Ding Hui <dinghui@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/scsi/ses.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index c2afba2a5414..9624298b9c89 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -690,6 +690,11 @@ static int ses_intf_add(struct device *cdev,
type_ptr[0] == ENCLOSURE_COMPONENT_ARRAY_DEVICE)
components += type_ptr[1];
}
+ if (components == 0) {
+ sdev_printk(KERN_ERR, sdev, "enclosure has no enumerated components\n");
+ goto err_free;
+ }
+
ses_dev->page1 = buf;
ses_dev->page1_len = len;
buf = NULL;