[PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv_region

[PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv_region

[Eric Auger]

In case the new region gets merged into another one, the nr
list node is freed. Checking its type while completing the
merge algorithm leads to a use-after-free. Use new->type
instead.

Fixes: 4dbd258ff63e ("iommu: Revisit iommu_insert_resv_region()
implementation")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Stable <stable@vger.kernel.org> #v5.3+

---

v2 -> v3:
- directly use new->type

v1 -> v2:
- remove spurious new line
---
 drivers/iommu/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d658c7c6a2ab..285ad4a4c7f2 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -313,7 +313,7 @@ int iommu_insert_resv_region(struct iommu_resv_region *new,
 		phys_addr_t top_end, iter_end = iter->start + iter->length - 1;
 
 		/* no merge needed on elements of different types than @nr */
-		if (iter->type != nr->type) {
+		if (iter->type != new->type) {
 			list_move_tail(&iter->list, &stack);
 			continue;
 		}
-- 
2.20.1

Re: [PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv_region

[Jerry Snitselaar]

On Tue Nov 26 19, Eric Auger wrote:
>In case the new region gets merged into another one, the nr
>list node is freed. Checking its type while completing the
>merge algorithm leads to a use-after-free. Use new->type
>instead.
>
>Fixes: 4dbd258ff63e ("iommu: Revisit iommu_insert_resv_region()
>implementation")
>Signed-off-by: Eric Auger <eric.auger@redhat.com>
>Reported-by: Qian Cai <cai@lca.pw>
>Cc: Stable <stable@vger.kernel.org> #v5.3+
>

Minor nit, but should the comment above list_for_each_entry_safe get
updated as well? Other than that, lgtm.

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>

>---
>
>v2 -> v3:
>- directly use new->type
>
>v1 -> v2:
>- remove spurious new line
>---
> drivers/iommu/iommu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>index d658c7c6a2ab..285ad4a4c7f2 100644
>--- a/drivers/iommu/iommu.c
>+++ b/drivers/iommu/iommu.c
>@@ -313,7 +313,7 @@ int iommu_insert_resv_region(struct iommu_resv_region *new,
> 		phys_addr_t top_end, iter_end = iter->start + iter->length - 1;
>
> 		/* no merge needed on elements of different types than @nr */
>-		if (iter->type != nr->type) {
>+		if (iter->type != new->type) {
> 			list_move_tail(&iter->list, &stack);
> 			continue;
> 		}
>-- 
>2.20.1
>
>_______________________________________________
>iommu mailing list
>iommu@lists.linux-foundation.org
>https://lists.linuxfoundation.org/mailman/listinfo/iommu
>

Re: [PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv_region

[Qian Cai]

> On Nov 26, 2019, at 5:27 AM, Eric Auger <eric.auger@redhat.com> wrote:
> 
> In case the new region gets merged into another one, the nr
> list node is freed. Checking its type while completing the
> merge algorithm leads to a use-after-free. Use new->type
> instead.
> 
> Fixes: 4dbd258ff63e ("iommu: Revisit iommu_insert_resv_region()
> implementation")
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reported-by: Qian Cai <cai@lca.pw>
> Cc: Stable <stable@vger.kernel.org> #v5.3+


Looks like Joerg is away for a few weeks. Could Andrew or Linus pick up this 
use-after-free?

> 
> ---
> 
> v2 -> v3:
> - directly use new->type
> 
> v1 -> v2:
> - remove spurious new line
> ---
> drivers/iommu/iommu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index d658c7c6a2ab..285ad4a4c7f2 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -313,7 +313,7 @@ int iommu_insert_resv_region(struct iommu_resv_region *new,
> 		phys_addr_t top_end, iter_end = iter->start + iter->length - 1;
> 
> 		/* no merge needed on elements of different types than @nr */
> -		if (iter->type != nr->type) {
> +		if (iter->type != new->type) {
> 			list_move_tail(&iter->list, &stack);
> 			continue;
> 		}
> -- 
> 2.20.1
> 

Re: [PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv_region

[Auger Eric]

Hi,
On 12/16/19 3:24 PM, Qian Cai wrote:
> 
> 
>> On Nov 26, 2019, at 5:27 AM, Eric Auger <eric.auger@redhat.com> wrote:
>>
>> In case the new region gets merged into another one, the nr
>> list node is freed. Checking its type while completing the
>> merge algorithm leads to a use-after-free. Use new->type
>> instead.
>>
>> Fixes: 4dbd258ff63e ("iommu: Revisit iommu_insert_resv_region()
>> implementation")
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> Reported-by: Qian Cai <cai@lca.pw>
>> Cc: Stable <stable@vger.kernel.org> #v5.3+
> 
> 
> Looks like Joerg is away for a few weeks. Could Andrew or Linus pick up this 
> use-after-free?
Thanks for the heads up. Indeed I was wondering why it hasn't been taken
yet.

Note the right version to pick up is the v4, reviewed by Jerry:
https://www.mail-archive.com/iommu@lists.linux-foundation.org/msg36226.html

Thanks

Eric
> 
>>
>> ---
>>
>> v2 -> v3:
>> - directly use new->type
>>
>> v1 -> v2:
>> - remove spurious new line
>> ---
>> drivers/iommu/iommu.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index d658c7c6a2ab..285ad4a4c7f2 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -313,7 +313,7 @@ int iommu_insert_resv_region(struct iommu_resv_region *new,
>> 		phys_addr_t top_end, iter_end = iter->start + iter->length - 1;
>>
>> 		/* no merge needed on elements of different types than @nr */
>> -		if (iter->type != nr->type) {
>> +		if (iter->type != new->type) {
>> 			list_move_tail(&iter->list, &stack);
>> 			continue;
>> 		}
>> -- 
>> 2.20.1
>>
> 

Re: [PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv_region

[Linus Torvalds]

On Mon, Dec 16, 2019 at 6:36 AM Auger Eric <eric.auger@redhat.com> wrote:
>On 12/16/19 3:24 PM, Qian Cai wrote:
> >
> > Looks like Joerg is away for a few weeks. Could Andrew or Linus pick up this
> > use-after-free?

I've taken it.

> Note the right version to pick up is the v4, reviewed by Jerry:
> https://www.mail-archive.com/iommu@lists.linux-foundation.org/msg36226.html

Btw, please use lore.kernel.org, it's much more convenient for me
(faster, and a single interface for me so that I don't have to always
figure out "what's the incantation to get the original raw email" that
so many archives make it hard to get).

                   Linus