Re: [PATCH] iommu/amd: Fix potential @entry null deref

[Joerg Roedel]

On Thu, Sep 10, 2020 at 06:16:21PM +0100, Joao Martins wrote:
> After commit 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn bit after
> programming IRTE"), smatch warns:
> 
>   drivers/iommu/amd/iommu.c:3870 amd_iommu_deactivate_guest_mode()
> warn: variable dereferenced before check 'entry' (see line 3867)
> 
> Fix this by moving the @valid assignment to after @entry has been checked
> for NULL.
> 
> Cc: Suravee Suthikulpanit 
> Fixes: 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn bit after programming 
> IRTE")
> Reported-by: Dan Carpenter 
> Signed-off-by: Joao Martins 
> ---
>  drivers/iommu/amd/iommu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Applied for v5.9, thanks.
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Re: [PATCH] iommu/amd: Fix potential @entry null deref

[Suravee Suthikulpanit]

Thanks for catching this.

On 9/11/20 12:16 AM, Joao Martins wrote:

After commit 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn bit after
programming IRTE"), smatch warns:

drivers/iommu/amd/iommu.c:3870 amd_iommu_deactivate_guest_mode()
 warn: variable dereferenced before check 'entry' (see line 3867)

Fix this by moving the @valid assignment to after @entry has been checked
for NULL.

Cc: Suravee Suthikulpanit 
Fixes: 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn bit after programming 
IRTE")
Reported-by: Dan Carpenter 
Signed-off-by: Joao Martins 
---
  drivers/iommu/amd/iommu.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 07ae8b93887e..8abe1c7ad45b 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3864,12 +3864,14 @@ int amd_iommu_deactivate_guest_mode(void *data)
struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
struct irq_cfg *cfg = ir_data->cfg;
-   u64 valid = entry->lo.fields_remap.valid;
+   u64 valid;
  
  	if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) ||

!entry || !entry->lo.fields_vapic.guest_mode)
return 0;
  
+	valid = entry->lo.fields_remap.valid;

+
entry->lo.val = 0;
entry->hi.val = 0;
  



Reviewed-by: Suravee Suthikulpanit 

Suravee
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[PATCH] iommu/amd: Fix potential @entry null deref

[Joao Martins]

After commit 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn bit after
programming IRTE"), smatch warns:

drivers/iommu/amd/iommu.c:3870 amd_iommu_deactivate_guest_mode()
warn: variable dereferenced before check 'entry' (see line 3867)

Fix this by moving the @valid assignment to after @entry has been checked
for NULL.

Cc: Suravee Suthikulpanit 
Fixes: 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn bit after programming 
IRTE")
Reported-by: Dan Carpenter 
Signed-off-by: Joao Martins 
---
 drivers/iommu/amd/iommu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 07ae8b93887e..8abe1c7ad45b 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3864,12 +3864,14 @@ int amd_iommu_deactivate_guest_mode(void *data)
struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
struct irq_cfg *cfg = ir_data->cfg;
-   u64 valid = entry->lo.fields_remap.valid;
+   u64 valid;
 
if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) ||
!entry || !entry->lo.fields_vapic.guest_mode)
return 0;
 
+   valid = entry->lo.fields_remap.valid;
+
entry->lo.val = 0;
entry->hi.val = 0;
 
-- 
2.17.1

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