| Message ID | 20250320112223.608320-1-rrichter@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] libnvdimm/labels: Fix divide error in nd_label_data_init() | expand |
On Thu, 20 Mar 2025, Robert Richter wrote: >If a faulty CXL memory device returns a broken zero LSA size in its >memory device information (Identify Memory Device (Opcode 4000h), CXL >spec. 3.1, 8.2.9.9.1.1), a divide error occurs in the libnvdimm >driver: > > Oops: divide error: 0000 [#1] PREEMPT SMP NOPTI > RIP: 0010:nd_label_data_init+0x10e/0x800 [libnvdimm] > >Code and flow: > >1) CXL Command 4000h returns LSA size = 0 >2) config_size is assigned to zero LSA size (CXL pmem driver): > >drivers/cxl/pmem.c: .config_size = mds->lsa_size, > >3) max_xfer is set to zero (nvdimm driver): > >drivers/nvdimm/label.c: max_xfer = min_t(size_t, ndd->nsarea.max_xfer, config_size); > >4) A subsequent DIV_ROUND_UP() causes a division by zero: > >drivers/nvdimm/label.c: /* Make our initial read size a multiple of max_xfer size */ >drivers/nvdimm/label.c: read_size = min(DIV_ROUND_UP(read_size, max_xfer) * max_xfer, >drivers/nvdimm/label.c- config_size); > >Fix this by checking the config size parameter by extending an >existing check. > >Signed-off-by: Robert Richter <rrichter@amd.com> >Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com> >Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Robert Richter wrote: > If a faulty CXL memory device returns a broken zero LSA size in its > memory device information (Identify Memory Device (Opcode 4000h), CXL > spec. 3.1, 8.2.9.9.1.1), a divide error occurs in the libnvdimm > driver: > > Oops: divide error: 0000 [#1] PREEMPT SMP NOPTI > RIP: 0010:nd_label_data_init+0x10e/0x800 [libnvdimm] > > Code and flow: > > 1) CXL Command 4000h returns LSA size = 0 > 2) config_size is assigned to zero LSA size (CXL pmem driver): > > drivers/cxl/pmem.c: .config_size = mds->lsa_size, > > 3) max_xfer is set to zero (nvdimm driver): > > drivers/nvdimm/label.c: max_xfer = min_t(size_t, ndd->nsarea.max_xfer, config_size); > > 4) A subsequent DIV_ROUND_UP() causes a division by zero: > > drivers/nvdimm/label.c: /* Make our initial read size a multiple of max_xfer size */ > drivers/nvdimm/label.c: read_size = min(DIV_ROUND_UP(read_size, max_xfer) * max_xfer, > drivers/nvdimm/label.c- config_size); > > Fix this by checking the config size parameter by extending an > existing check. > > Signed-off-by: Robert Richter <rrichter@amd.com> > Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com> > Reviewed-by: Ira Weiny <ira.weiny@intel.com> Applied to nvdimm/next Thanks, Ira [snip]
diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c index 082253a3a956..04f4a049599a 100644 --- a/drivers/nvdimm/label.c +++ b/drivers/nvdimm/label.c @@ -442,7 +442,8 @@ int nd_label_data_init(struct nvdimm_drvdata *ndd) if (ndd->data) return 0; - if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0) { + if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0 || + ndd->nsarea.config_size == 0) { dev_dbg(ndd->dev, "failed to init config data area: (%u:%u)\n", ndd->nsarea.max_xfer, ndd->nsarea.config_size); return -ENXIO;