| Message ID | 20211007174957.2080-1-decui@microsoft.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] scsi: core: Fix shost->cmd_per_lun calculation in scsi_add_host_with_dma() | expand |
> -----Original Message----- > From: Dexuan Cui <decui@microsoft.com> > Sent: Thursday, October 7, 2021 1:50 PM > To: KY Srinivasan <kys@microsoft.com>; Stephen Hemminger > <sthemmin@microsoft.com>; wei.liu@kernel.org; jejb@linux.ibm.com; > martin.petersen@oracle.com; Haiyang Zhang <haiyangz@microsoft.com>; > ming.lei@redhat.com; bvanassche@acm.org; john.garry@huawei.com; linux- > scsi@vger.kernel.org; linux-hyperv@vger.kernel.org; Long Li > <longli@microsoft.com>; Michael Kelley <mikelley@microsoft.com> > Cc: linux-kernel@vger.kernel.org; Dexuan Cui <decui@microsoft.com>; > stable@vger.kernel.org > Subject: [PATCH v2] scsi: core: Fix shost->cmd_per_lun calculation in > scsi_add_host_with_dma() > > After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during > boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a > negative number (the below numbers may differ in different kernel > versions): > in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets > 'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets > 'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue > to > 352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX. > > Use min_t(int, ...) to fix the issue. > > Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at > can_queue") > Cc: stable@vger.kernel.org > Signed-off-by: Dexuan Cui <decui@microsoft.com> > --- > > v1 tried to fix the issue by changing the storvsc driver: > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Flwn.ne > t%2Fml%2Flinux- > kernel%2FBYAPR21MB1270BBC14D5F1AE69FC31A16BFB09%40BYAPR21MB1270.namprd21 > .prod.outlook.com%2F&data=04%7C01%7Chaiyangz%40microsoft.com%7C366e6 > d0bf755492c631c08d989baf4b9%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7 > C637692258384408217%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoi > V2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=RbNgx1aBBBzfHC3p > EdKyBZWaaQIQXS3U%2FItEQUe4NfQ%3D&reserved=0 > > v2 directly fixes the scsi core change instead as Michael Kelley and > John Garry suggested (refer to the above link). > > drivers/scsi/hosts.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 3f6f14f0cafb..24b72ee4246f 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -220,7 +220,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, > struct device *dev, > goto fail; > } > > - shost->cmd_per_lun = min_t(short, shost->cmd_per_lun, > + /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */ > + shost->cmd_per_lun = min_t(int, shost->cmd_per_lun, > shost->can_queue); Since shost->can_queue is int, the min_t type should also be int (the longer type of the two vars). Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
On 07/10/2021 18:49, Dexuan Cui wrote: > After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during > boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a > negative number (the below numbers may differ in different kernel versions): > in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets > 'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets > 'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue to > 352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX. I think that you just need to mention that if can_queue exceeds SHRT_MAX, then there is a data truncation issue. > > Use min_t(int, ...) to fix the issue. > > Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue") > Cc: stable@vger.kernel.org > Signed-off-by: Dexuan Cui <decui@microsoft.com> It looks ok, I'd just like to test it a bit more. Thanks, John > --- > > v1 tried to fix the issue by changing the storvsc driver: > https://lwn.net/ml/linux-kernel/BYAPR21MB1270BBC14D5F1AE69FC31A16BFB09@BYAPR21MB1270.namprd21.prod.outlook.com/ > > v2 directly fixes the scsi core change instead as Michael Kelley and > John Garry suggested (refer to the above link). To be fair, it was Michael's suggestion > > drivers/scsi/hosts.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 3f6f14f0cafb..24b72ee4246f 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -220,7 +220,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > goto fail; > } > > - shost->cmd_per_lun = min_t(short, shost->cmd_per_lun, > + /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */ > + shost->cmd_per_lun = min_t(int, shost->cmd_per_lun, > shost->can_queue); > > error = scsi_init_sense_cache(shost); >
> From: John Garry <john.garry@huawei.com> > Sent: Thursday, October 7, 2021 2:42 PM > > On 07/10/2021 18:49, Dexuan Cui wrote: > > After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during > > boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a > > negative number (the below numbers may differ in different kernel versions): > > in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets > > 'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets > > 'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue to > > 352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX. > > I think that you just need to mention that if can_queue exceeds > SHRT_MAX, then there is a data truncation issue. I just hoped the explanation how the too big 'can_queue' value is generated is helpful. OK, I think I can change the commit log to: After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during boot because the hv_storvsc driver sets scsi_driver.can_queue to an "int" value that exceeds SHRT_MAX, and hence scsi_add_host_with_dma() sets shost->cmd_per_lun to a negative "short" number. Use min_t(int, ...) to fix the issue. > It looks ok, I'd just like to test it a bit more. > > Thanks, > John Thanks! I'll post v3 with the above commit log, and I look forward to your review/test. > > v2 directly fixes the scsi core change instead as Michael Kelley and > > John Garry suggested (refer to the above link). > > To be fair, it was Michael's suggestion Yeah. Michael always gives good suggstions when reviewing patches. :-)
On Thu, Oct 07, 2021 at 10:49:57AM -0700, Dexuan Cui wrote: > After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during > boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a > negative number (the below numbers may differ in different kernel versions): > in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets > 'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets > 'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue to > 352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX. > > Use min_t(int, ...) to fix the issue. > > Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue") > Cc: stable@vger.kernel.org > Signed-off-by: Dexuan Cui <decui@microsoft.com> > --- > > v1 tried to fix the issue by changing the storvsc driver: > https://lwn.net/ml/linux-kernel/BYAPR21MB1270BBC14D5F1AE69FC31A16BFB09@BYAPR21MB1270.namprd21.prod.outlook.com/ > > v2 directly fixes the scsi core change instead as Michael Kelley and > John Garry suggested (refer to the above link). > > drivers/scsi/hosts.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 3f6f14f0cafb..24b72ee4246f 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -220,7 +220,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > goto fail; > } > > - shost->cmd_per_lun = min_t(short, shost->cmd_per_lun, > + /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */ > + shost->cmd_per_lun = min_t(int, shost->cmd_per_lun, > shost->can_queue); Looks fine: Reviewed-by: Ming Lei <ming.lei@redhat.com>
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index 3f6f14f0cafb..24b72ee4246f 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -220,7 +220,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, goto fail; } - shost->cmd_per_lun = min_t(short, shost->cmd_per_lun, + /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */ + shost->cmd_per_lun = min_t(int, shost->cmd_per_lun, shost->can_queue); error = scsi_init_sense_cache(shost);
After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a negative number (the below numbers may differ in different kernel versions): in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets 'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets 'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue to 352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX. Use min_t(int, ...) to fix the issue. Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue") Cc: stable@vger.kernel.org Signed-off-by: Dexuan Cui <decui@microsoft.com> --- v1 tried to fix the issue by changing the storvsc driver: https://lwn.net/ml/linux-kernel/BYAPR21MB1270BBC14D5F1AE69FC31A16BFB09@BYAPR21MB1270.namprd21.prod.outlook.com/ v2 directly fixes the scsi core change instead as Michael Kelley and John Garry suggested (refer to the above link). drivers/scsi/hosts.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)