Hi, Rafael > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of Rafael J. > Wysocki > Subject: [PATCH] ACPI / DMAR: Avoid passing NULL to acpi_put_table() > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > 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@xxxxxxxxxxxxxxxxxxxx> > 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@xxxxxxxxx> Thanks for looking into this issue. The patch fixes the caller side and thus looks very good from my opinion. Acked-by: Lv Zheng <lv.zheng@xxxxxxxxx> Best regards Lv > --- > drivers/iommu/dmar.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > Index: linux-pm/drivers/iommu/dmar.c > =================================================================== > --- linux-pm.orig/drivers/iommu/dmar.c > +++ linux-pm/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; > > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
