+ mm-swap-fix-potensial-buffer-overflow-in-setup_clusters.patch added to mm-new branch

+ mm-swap-fix-potensial-buffer-overflow-in-setup_clusters.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm: swap: fix potensial buffer overflow in setup_clusters()
has been added to the -mm mm-new branch.  Its filename is
     mm-swap-fix-potensial-buffer-overflow-in-setup_clusters.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-fix-potensial-buffer-overflow-in-setup_clusters.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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------------------------------------------------------
From: Kemeng Shi <shikemeng@huaweicloud.com>
Subject: mm: swap: fix potensial buffer overflow in setup_clusters()
Date: Thu, 22 May 2025 20:25:53 +0800

In setup_swap_map(), we only ensure badpages are in range (0, last_page]. 
As maxpages might be < last_page, setup_clusters() will encounter a buffer
overflow when a badpage is >= maxpages.

Only call inc_cluster_info_page() for badpage which is < maxpages to fix
the issue.

Link: https://lkml.kernel.org/r/20250522122554.12209-4-shikemeng@huaweicloud.com
Fixes: b843786b0bd01 ("mm: swapfile: fix SSD detection with swapfile on btrfs")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: <stable@vger.kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swapfile.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/mm/swapfile.c~mm-swap-fix-potensial-buffer-overflow-in-setup_clusters
+++ a/mm/swapfile.c
@@ -3208,9 +3208,13 @@ static struct swap_cluster_info *setup_c
 	 * and the EOF part of the last cluster.
 	 */
 	inc_cluster_info_page(si, cluster_info, 0);
-	for (i = 0; i < swap_header->info.nr_badpages; i++)
-		inc_cluster_info_page(si, cluster_info,
-				      swap_header->info.badpages[i]);
+	for (i = 0; i < swap_header->info.nr_badpages; i++) {
+		unsigned int page_nr = swap_header->info.badpages[i];
+
+		if (page_nr >= maxpages)
+			continue;
+		inc_cluster_info_page(si, cluster_info, page_nr);
+	}
 	for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++)
 		inc_cluster_info_page(si, cluster_info, i);
 
_

Patches currently in -mm which might be from shikemeng@huaweicloud.com are

mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch
mm-shmem-add-missing-shmem_unacct_size-in-__shmem_file_setup.patch
mm-shmem-fix-potential-dead-loop-in-shmem_unuse.patch
mm-shmem-only-remove-inode-from-swaplist-when-its-swapped-page-count-is-0.patch
mm-shmem-remove-unneeded-xa_is_value-check-in-shmem_unuse_swap_entries.patch
mm-swap-move-nr_swap_pages-counter-decrement-from-folio_alloc_swap-to-swap_range_alloc.patch
mm-swap-correctly-use-maxpages-in-swapon-syscall-to-avoid-potensial-deadloop.patch
mm-swap-fix-potensial-buffer-overflow-in-setup_clusters.patch
mm-swap-remove-stale-comment-stale-comment-in-cluster_alloc_swap_entry.patch