From: Li Ming ming4.li@intel.com

mainline inclusion from mainline-v6.10-rc7 commit 84ec985944ef34a34a1605b93ce401aa8737af96 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGEOB CVE: CVE-2024-41085

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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When CXL subsystem is auto-assembling a pmem region during cxl endpoint port probing, always hit below calltrace.

BUG: kernel NULL pointer dereference, address: 0000000000000078 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page RIP: 0010:cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem] Call Trace: <TASK> ? __die+0x24/0x70 ? page_fault_oops+0x82/0x160 ? do_user_addr_fault+0x65/0x6b0 ? exc_page_fault+0x7d/0x170 ? asm_exc_page_fault+0x26/0x30 ? cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem] ? cxl_pmem_region_probe+0x1ac/0x360 [cxl_pmem] cxl_bus_probe+0x1b/0x60 [cxl_core] really_probe+0x173/0x410 ? __pfx___device_attach_driver+0x10/0x10 __driver_probe_device+0x80/0x170 driver_probe_device+0x1e/0x90 __device_attach_driver+0x90/0x120 bus_for_each_drv+0x84/0xe0 __device_attach+0xbc/0x1f0 bus_probe_device+0x90/0xa0 device_add+0x51c/0x710 devm_cxl_add_pmem_region+0x1b5/0x380 [cxl_core] cxl_bus_probe+0x1b/0x60 [cxl_core]

The cxl_nvd of the memdev needs to be available during the pmem region probe. Currently the cxl_nvd is registered after the endpoint port probe. The endpoint probe, in the case of autoassembly of regions, can cause a pmem region probe requiring the not yet available cxl_nvd. Adjust the sequence so this dependency is met.

This requires adding a port parameter to cxl_find_nvdimm_bridge() that can be used to query the ancestor root port. The endpoint port is not yet available, but will share a common ancestor with its parent, so start the query from there instead.

Fixes: f17b558d6663 ("cxl/pmem: Refactor nvdimm device registration, delete the workqueue") Co-developed-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Li Ming ming4.li@intel.com Tested-by: Alison Schofield alison.schofield@intel.com Reviewed-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Alison Schofield alison.schofield@intel.com Link: https://patch.msgid.link/20240612064423.2567625-1-ming4.li@intel.com Signed-off-by: Dave Jiang dave.jiang@intel.com Conflicts: drivers/cxl/core/pmem.c drivers/cxl/core/region.c [wangxiongfeng: fix conflicts in cxl_find_nvdimm_bridge() and cxl_pmem_region_alloc().] Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com --- drivers/cxl/core/pmem.c | 21 ++++++++++++++------- drivers/cxl/core/region.c | 2 +- drivers/cxl/cxl.h | 4 ++-- drivers/cxl/mem.c | 17 +++++++++-------- 4 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c index fc94f5240327..1da3541c1e1b 100644 --- a/drivers/cxl/core/pmem.c +++ b/drivers/cxl/core/pmem.c @@ -62,16 +62,21 @@ static int match_nvdimm_bridge(struct device *dev, void *data) return is_cxl_nvdimm_bridge(dev); }

-struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd) +/** + * cxl_find_nvdimm_bridge() - find a bridge device relative to a port + * @port: any descendant port of an nvdimm-bridge associated + * root-cxl-port + */ +struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port) { - struct cxl_port *port = find_cxl_root(cxlmd->endpoint); + struct cxl_port *cxl_root = find_cxl_root(port); struct device *dev;

- if (!port) + if (!cxl_root) return NULL;

- dev = device_find_child(&port->dev, NULL, match_nvdimm_bridge); - put_device(&port->dev); + dev = device_find_child(&cxl_root->dev, NULL, match_nvdimm_bridge); + put_device(&cxl_root->dev);

if (!dev) return NULL; @@ -242,18 +247,20 @@ static void cxlmd_release_nvdimm(void *_cxlmd)

/** * devm_cxl_add_nvdimm() - add a bridge between a cxl_memdev and an nvdimm + * @parent_port: parent port for the (to be added) @cxlmd endpoint port * @cxlmd: cxl_memdev instance that will perform LIBNVDIMM operations * * Return: 0 on success negative error code on failure. */ -int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd) +int devm_cxl_add_nvdimm(struct cxl_port *parent_port, + struct cxl_memdev *cxlmd) { struct cxl_nvdimm_bridge *cxl_nvb; struct cxl_nvdimm *cxl_nvd; struct device *dev; int rc;

- cxl_nvb = cxl_find_nvdimm_bridge(cxlmd); + cxl_nvb = cxl_find_nvdimm_bridge(parent_port); if (!cxl_nvb) return -ENODEV;

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 6f06255012f0..94e0af80d0b4 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -2547,7 +2547,7 @@ static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr) * bridge for one device is the same for all. */ if (i == 0) { - cxl_nvb = cxl_find_nvdimm_bridge(cxlmd); + cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint); if (!cxl_nvb) { cxlr_pmem = ERR_PTR(-ENODEV); goto out; diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 47fc7f692ae9..3b0b694a95b1 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -805,8 +805,8 @@ struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host, struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev); bool is_cxl_nvdimm(struct device *dev); bool is_cxl_nvdimm_bridge(struct device *dev); -int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd); -struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd); +int devm_cxl_add_nvdimm(struct cxl_port *parent_port, struct cxl_memdev *cxlmd); +struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port);

#ifdef CONFIG_CXL_REGION bool is_cxl_pmem_region(struct device *dev); diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c index e087febf9af0..22b260d261e4 100644 --- a/drivers/cxl/mem.c +++ b/drivers/cxl/mem.c @@ -152,6 +152,15 @@ static int cxl_mem_probe(struct device *dev) return -ENXIO; }

+ if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) { + rc = devm_cxl_add_nvdimm(parent_port, cxlmd); + if (rc) { + if (rc == -ENODEV) + dev_info(dev, "PMEM disabled by platform\n"); + return rc; + } + } + if (dport->rch) endpoint_parent = parent_port->uport_dev; else @@ -174,14 +183,6 @@ static int cxl_mem_probe(struct device *dev) if (rc) return rc;

- if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) { - rc = devm_cxl_add_nvdimm(cxlmd); - if (rc == -ENODEV) - dev_info(dev, "PMEM disabled by platform\n"); - else - return rc; - } - /* * The kernel may be operating out of CXL memory on this device, * there is no spec defined way to determine whether this device