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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-01-05 04:13:31 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-01-05 17:10:52 +0300
commit696c7f8e0373026e8bfb29b2d9ff2d0a92059d4d (patch)
treeb933c78b92d1887fdb28dc7be93af426053da036 /drivers/iommu/dmar.c
parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
downloadlinux-696c7f8e0373026e8bfb29b2d9ff2d0a92059d4d.tar.xz
ACPI / DMAR: Avoid passing NULL to acpi_put_table()
Linus reported that commit 174cc7187e6f "ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux kernel" added a new warning on his desktop system: ACPI Warning: Table ffffffff9fe6c0a0, Validation count is zero before decrement which turns out to come from the acpi_put_table() in detect_intel_iommu(). This happens if the DMAR table is not present in which case NULL is passed to acpi_put_table() which doesn't check against that and attempts to handle it regardless. For this reason, check the pointer passed to acpi_put_table() before invoking it. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Fixes: 6b11d1d67713 ("ACPI / osl: Remove acpi_get_table_with_size()/early_acpi_os_unmap_memory() users") Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/iommu/dmar.c')
-rw-r--r--drivers/iommu/dmar.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index a88576d50740..8ccbd7023194 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -903,8 +903,10 @@ int __init detect_intel_iommu(void)
x86_init.iommu.iommu_init = intel_iommu_init;
#endif
- acpi_put_table(dmar_tbl);
- dmar_tbl = NULL;
+ if (dmar_tbl) {
+ acpi_put_table(dmar_tbl);
+ dmar_tbl = NULL;
+ }
up_write(&dmar_global_lock);
return ret ? 1 : -ENODEV;