linux-kernel - [PATCH v2 1/2] mm/kmap: Add kmap_local_page_try_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250321112436.1739876-2-jfalempe@redhat.com>
Date: Fri, 21 Mar 2025 12:16:55 +0100
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Ryosuke Yasuoka <ryasuoka@...hat.com>,
	Javier Martinez Canillas <javierm@...hat.com>,
	Wei Yang <richard.weiyang@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	John Ogness <john.ogness@...utronix.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-mm@...ck.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Cc: Jocelyn Falempe <jfalempe@...hat.com>,
	Simona Vetter <simona.vetter@...ll.ch>
Subject: [PATCH v2 1/2] mm/kmap: Add kmap_local_page_try_from_panic()

kmap_local_page() can be unsafe to call from a panic handler, if
CONFIG_HIGHMEM is set, and the page is in the highmem zone.
So add kmap_local_page_try_from_panic() to handle this case.

Suggested-by: Simona Vetter <simona.vetter@...ll.ch>
Signed-off-by: Jocelyn Falempe <jfalempe@...hat.com>
---
 include/linux/highmem-internal.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
index dd100e849f5e0..5d089b0ca56de 100644
--- a/include/linux/highmem-internal.h
+++ b/include/linux/highmem-internal.h
@@ -73,6 +73,13 @@ static inline void *kmap_local_page(struct page *page)
 	return __kmap_local_page_prot(page, kmap_prot);
 }
 
+static inline void *kmap_local_page_try_from_panic(struct page *page)
+{
+	if (!PageHighMem(page))
+		return page_address(page);
+	return NULL;
+}
+
 static inline void *kmap_local_folio(struct folio *folio, size_t offset)
 {
 	struct page *page = folio_page(folio, offset / PAGE_SIZE);
@@ -180,6 +187,11 @@ static inline void *kmap_local_page(struct page *page)
 	return page_address(page);
 }
 
+static inline void *kmap_local_page_try_from_panic(struct page *page)
+{
+	return page_address(page);
+}
+
 static inline void *kmap_local_folio(struct folio *folio, size_t offset)
 {
 	return page_address(&folio->page) + offset;
-- 
2.47.1