5.4-stable review patch. If anyone has any objections, please let me know.
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From: Robert Richter rrichter@amd.com
[ Upstream commit ef1d3455bbc1922f94a91ed58d3d7db440652959 ]
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 Link: https://patch.msgid.link/20250320112223.608320-1-rrichter@amd.com Signed-off-by: Ira Weiny ira.weiny@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 9251441fd8a35..5251058adc4d1 100644 --- a/drivers/nvdimm/label.c +++ b/drivers/nvdimm/label.c @@ -421,7 +421,8 @@ 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;