2019-11-26 10:32:38

by Eric Auger

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

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 <[email protected]>
Reported-by: Qian Cai <[email protected]>
Cc: Stable <[email protected]> #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

2019-11-26 17:23:14

by Jerry Snitselaar

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

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 <[email protected]>
>Reported-by: Qian Cai <[email protected]>
>Cc: Stable <[email protected]> #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 <[email protected]>

>---
>
>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
>
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