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Message-ID: <4a8913e7-567f-2b88-6bb8-0305569f866f@sangfor.com.cn>
Date: Wed, 5 Apr 2023 12:49:13 +0800
From: Ding Hui <dinghui@...gfor.com.cn>
To: Jiri Kosina <jikos@...nel.org>,
James Bottomley <jejb@...ux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@...cle.com>,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
Michal Kolar <mich.k@...nam.cz>
Subject: Re: [PATCH v2] scsi: ses: Handle enclosure with just a primary
component gracefully
On 2023/4/5 5:41, Jiri Kosina wrote:
> 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@...gfor.com.cn>.
>>
>> 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.
>
I think we should remove the check, because the edev->components
represented the effectiveness of array pointers, so we need check
edev->components firstly instead of checking edev->component[0].scratch.
If edev->components is 0, we won't enter the for loop, so don't worry
about dereference scomp.
> Please find v2 below, with this hunk removed, and Tested-by: added.
>
>
>
>
>
> From: Jiri Kosina <jkosina@...e.cz>
> 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@...gfor.com.cn>.
>
> 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@...nam.cz>
> Tested-by: Michal Kolar <mich.k@...nam.cz>
> Originally-by: Ding Hui <dinghui@...gfor.com.cn>
> Cc: stable@...r.kernel.org
> Fixes: 3fe97ff3d9493 ("scsi: ses: Don't attach if enclosure has no components")
> Signed-off-by: Jiri Kosina <jkosina@...e.cz>
> ---
>
> 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);
--
Thanks,
-dinghui
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