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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Eric Auger <eric.auger@redhat.com>,
        Qian Cai <cai@lca.pw>, Jerry Snitselaar <jsnitsel@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 5.4 367/434] iommu: fix KASAN use-after-free in iommu_insert_resv_region
Date:   Sun, 29 Dec 2019 18:27:00 +0100
Message-Id: <20191229172726.351162300@linuxfoundation.org>
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From: Eric Auger <eric.auger@redhat.com>

commit 4c80ba392bf603d468ea827d902f8e7b2505fbf4 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iommu/iommu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -312,8 +312,8 @@ int iommu_insert_resv_region(struct iomm
 	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;
 		}