4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 0919871ac37fdcf46c7657da0f1742efe096b399 ]
Possible race accessing memdev structures after dropping the mutex. Dan Williams says this could race against another thread that is doing:
# echo "ACPI0012:00" > /sys/bus/acpi/drivers/nfit/unbind
Reported-by: Jane Chu jane.chu@oracle.com Fixes: 23222f8f8dce ("acpi, nfit: Add function to look up nvdimm...") Signed-off-by: Tony Luck tony.luck@intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/nfit/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index 8535e7999769b..2a2d7ec772526 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -724,6 +724,7 @@ int nfit_get_smbios_id(u32 device_handle, u16 *flags) struct acpi_nfit_memory_map *memdev; struct acpi_nfit_desc *acpi_desc; struct nfit_mem *nfit_mem; + u16 physical_id;
mutex_lock(&acpi_desc_lock); list_for_each_entry(acpi_desc, &acpi_descs, list) { @@ -731,10 +732,11 @@ int nfit_get_smbios_id(u32 device_handle, u16 *flags) list_for_each_entry(nfit_mem, &acpi_desc->dimms, list) { memdev = __to_nfit_memdev(nfit_mem); if (memdev->device_handle == device_handle) { + *flags = memdev->flags; + physical_id = memdev->physical_id; mutex_unlock(&acpi_desc->init_mutex); mutex_unlock(&acpi_desc_lock); - *flags = memdev->flags; - return memdev->physical_id; + return physical_id; } } mutex_unlock(&acpi_desc->init_mutex);