linux-kernel - [PATCH v3] iommu: fix KASAN use-after-free in iommu_insert_resv

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Message-Id: <20191126102743.3269-1-eric.auger@redhat.com>
Date:   Tue, 26 Nov 2019 11:27:43 +0100
From:   Eric Auger <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, eric.auger@...hat.com, joro@...tes.org,
        hch@....de, cai@....pw, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
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 <eric.auger@...hat.com>
Reported-by: Qian Cai <cai@....pw>
Cc: Stable <stable@...r.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