On 3/19/2025 12:32 PM, Robert Richter wrote:
If a 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); drivers/nvdimm/label.c: if (read_size < max_xfer) { drivers/nvdimm/label.c- /* trim waste */ 4) DIV_ROUND_UP() causes division by zero: drivers/nvdimm/label.c: max_xfer -= ((max_xfer - 1) - (config_size - 1) % max_xfer) / drivers/nvdimm/label.c: DIV_ROUND_UP(config_size, max_xfer); drivers/nvdimm/label.c- /* make certain we read indexes in exactly 1 read */ drivers/nvdimm/label.c: if (max_xfer < read_size) drivers/nvdimm/label.c: max_xfer = read_size; drivers/nvdimm/label.c- } Fix this by checking the config size parameter by extending an existing check. Signed-off-by: Robert Richter <[email protected]>
LGTM Reviewed-by: Pankaj Gupta <[email protected]>
--- drivers/nvdimm/label.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) 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;
