Date: Mon, 24 Aug 2026 18:54:16 -0700
To: mm-commits@vger.kernel.org,ziy@nvidia.com,vbabka@kernel.org,surenb@google.com,mhocko@suse.com,jhubbard@nvidia.com,hannes@cmpxchg.org,akpm@linux-foundation.org,liuye@kylinos.cn,akpm@linux-foundation.org
From: Andrew Morton <akpm@linux-foundation.org>
Subject: [merged mm-stable] mm-debug_page_alloc-fix-null-buf-in-debug_guardpage_minorder_setup.patch removed from -mm tree
Message-Id: <20260825015417.372961F00A3A@smtp.kernel.org>
Precedence: bulk


The quilt patch titled
     Subject: mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
has been removed from the -mm tree.  Its filename was
     mm-debug_page_alloc-fix-null-buf-in-debug_guardpage_minorder_setup.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Ye Liu <liuye@kylinos.cn>
Subject: mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
Date: Thu, 6 Aug 2026 08:45:55 +0800

If the kernel command line includes "debug_guardpage_minorder" without an
equals sign (i.e., no value is provided), the early parameter parser
passes a NULL buf pointer to the setup function.

kstrtouint() does not perform a NULL check on its input and calls directly
into kstrtoull() which dereferences s[0] unconditionally, leading to a
NULL pointer dereference and early boot crash.

Additionally, the error path's pr_err("%s", buf) would also crash with a
NULL format argument.

Link: https://lore.kernel.org/20260806004556.2633049-1-ye.liu@linux.dev
Fixes: c0a32fc5a2e4 ("mm: more intensive memory corruption debugging")
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- a/mm/debug_page_alloc.c~mm-debug_page_alloc-fix-null-buf-in-debug_guardpage_minorder_setup
+++ a/mm/debug_page_alloc.c
@@ -22,8 +22,8 @@ static int __init debug_guardpage_minord
 {
 	unsigned int res;
 
-	if (kstrtouint(buf, 10, &res) < 0 ||  res > MAX_PAGE_ORDER / 2) {
-		pr_err("Bad debug_guardpage_minorder value: %s\n", buf);
+	if (!buf || kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
+		pr_err("Bad debug_guardpage_minorder value: %s\n", buf ?: "(missing)");
 		return 0;
 	}
 	_debug_guardpage_minorder = res;
_

Patches currently in -mm which might be from liuye@kylinos.cn are