FAILED: patch "[PATCH] dm vdo indexer: validate record page numbers better" failed to apply to 5.15-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x e3683a76a313a81f3f7bc7f65e4fc1e61232838b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107055838-failed-5.15-e3683a76a313@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From e3683a76a313a81f3f7bc7f65e4fc1e61232838b Mon Sep 17 00:00:00 2001
From: Matthew Sakai <msakai@redhat.com>
Date: Tue, 11 Aug 2026 15:02:34 -0400
Subject: [PATCH] dm vdo indexer: validate record page numbers better

Move the record_page_number validation check into the
chapter index lookup function in order to detect (and
discard) corrupted values on all paths.

Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
---
 drivers/md/dm-vdo/indexer/chapter-index.c | 15 +++++++++++----
 drivers/md/dm-vdo/indexer/volume.c        |  6 ------
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/md/dm-vdo/indexer/chapter-index.c b/drivers/md/dm-vdo/indexer/chapter-index.c
index bb3b0ab5d50dc..9fb9e59238d4c 100644
--- a/drivers/md/dm-vdo/indexer/chapter-index.c
+++ b/drivers/md/dm-vdo/indexer/chapter-index.c
@@ -284,10 +284,17 @@ int uds_search_chapter_index_page(struct delta_index_page *index_page,
 	if (result != UDS_SUCCESS)
 		return result;
 
-	if (was_entry_found(&entry, address))
-		*record_page_ptr = uds_get_delta_entry_value(&entry);
-	else
+	if (!was_entry_found(&entry, address)) {
 		*record_page_ptr = NO_CHAPTER_INDEX_ENTRY;
+		return UDS_SUCCESS;
+	}
 
-	return UDS_SUCCESS;
+	*record_page_ptr = uds_get_delta_entry_value(&entry);
+	result = VDO_ASSERT(*record_page_ptr < geometry->record_pages_per_chapter,
+			    "0 <= %d < %u", *record_page_ptr,
+			    geometry->record_pages_per_chapter);
+	if (result != VDO_SUCCESS)
+		*record_page_ptr = NO_CHAPTER_INDEX_ENTRY;
+
+	return result;
 }
diff --git a/drivers/md/dm-vdo/indexer/volume.c b/drivers/md/dm-vdo/indexer/volume.c
index 78c3729f1f65e..38e51fa1cbd05 100644
--- a/drivers/md/dm-vdo/indexer/volume.c
+++ b/drivers/md/dm-vdo/indexer/volume.c
@@ -891,12 +891,6 @@ int uds_search_cached_record_page(struct volume *volume, struct uds_request *req
 	if (record_page_number == NO_CHAPTER_INDEX_ENTRY)
 		return UDS_SUCCESS;
 
-	result = VDO_ASSERT(record_page_number < geometry->record_pages_per_chapter,
-			    "0 <= %d < %u", record_page_number,
-			    geometry->record_pages_per_chapter);
-	if (result != VDO_SUCCESS)
-		return result;
-
 	page_number = geometry->index_pages_per_chapter + record_page_number;
 
 	physical_page = map_to_physical_page(&volume->geometry, chapter, page_number);
-- 
2.53.0