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 <rrich...@amd.com>
Reviewed-by: Pankaj Gupta <pankaj.gu...@amd.com>
Reviewed-by: Ira Weiny <ira.we...@intel.com>
Reviewed-by: Davidlohr Bueso <d...@stgolabs.net>
