From 670e4e88f3b1a88a5a089be329b95c51592973ee Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Thu, 12 Oct 2023 11:53:42 -0700 Subject: [PATCH] cxl: Add checksum verification to CDAT from CXL A CDAT table is available from a CXL device. The table is read by the driver and cached in software. With the CXL subsystem needing to parse the CDAT table, the checksum should be verified. Add checksum verification after the CDAT table is read from device. Reviewed-by: Ira Weiny Reviewed-by: Jonathan Cameron Reviewed-by: Davidlohr Bueso Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/169713682277.2205276.2687265961314933628.stgit@djiang5-mobl3 Signed-off-by: Dan Williams --- drivers/cxl/core/pci.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index c7a7887ebdcf..9321a3865c30 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -595,6 +595,16 @@ static int cxl_cdat_read_table(struct device *dev, return 0; } +static unsigned char cdat_checksum(void *buf, size_t size) +{ + unsigned char sum, *data = buf; + size_t i; + + for (sum = 0, i = 0; i < size; i++) + sum += data[i]; + return sum; +} + /** * read_cdat_data - Read the CDAT data on this port * @port: Port to read data from @@ -634,15 +644,21 @@ void read_cdat_data(struct cxl_port *port) return; rc = cxl_cdat_read_table(dev, cdat_doe, cdat_table, &cdat_length); - if (rc) { - /* Don't leave table data allocated on error */ - devm_kfree(dev, cdat_table); - dev_err(dev, "CDAT data read error\n"); - return; - } + if (rc) + goto err; - port->cdat.table = cdat_table + sizeof(__le32); + cdat_table = cdat_table + sizeof(__le32); + if (cdat_checksum(cdat_table, cdat_length)) + goto err; + + port->cdat.table = cdat_table; port->cdat.length = cdat_length; + return; + +err: + /* Don't leave table data allocated on error */ + devm_kfree(dev, cdat_table); + dev_err(dev, "Failed to read/validate CDAT.\n"); } EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);