From: Eric Auger <eric.auger@redhat.com>
Date: Tue, 26 Nov 2019 18:54:13 +0100
Subject: iommu: fix KASAN use-after-free in iommu_insert_resv_region
Git-commit: 4c80ba392bf603d468ea827d902f8e7b2505fbf4
Patch-mainline: v5.5-rc3
References: bsc#1175713

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>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Cc: Stable <stable@vger.kernel.org> #v5.3+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index db7bfd4f2d20..1c3f2a3035c1 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -312,8 +312,8 @@ int iommu_insert_resv_region(struct iommu_resv_region *new,
 	list_for_each_entry_safe(iter, tmp, regions, list) {
 		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) {
+		/* no merge needed on elements of different types than @new */
+		if (iter->type != new->type) {
 			list_move_tail(&iter->list, &stack);
 			continue;
 		}