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  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]
Date:   Wed, 13 Jan 2021 16:43:21 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     akpm@...ux-foundation.org
Cc:     Qian Cai <cai@....pw>, Michal Hocko <mhocko@...e.com>,
        Oscar Salvador <osalvador@...e.de>,
        David Hildenbrand <david@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>, linux-mm@...ck.org,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/5] mm: Teach pfn_to_online_page() to consider
 subsection validity

pfn_section_valid() determines pfn validity on subsection granularity
where pfn_valid() may be limited to coarse section granularity.
Explicitly validate subsections after pfn_valid() succeeds.

Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()")
Cc: Qian Cai <cai@....pw>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Oscar Salvador <osalvador@...e.de>
Reported-by: David Hildenbrand <david@...hat.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 mm/memory_hotplug.c |   23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 55a69d4396e7..d0c81f7a3347 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -308,11 +308,26 @@ static int check_hotplug_memory_addressable(unsigned long pfn,
 struct page *pfn_to_online_page(unsigned long pfn)
 {
 	unsigned long nr = pfn_to_section_nr(pfn);
+	struct mem_section *ms;
+
+	if (nr >= NR_MEM_SECTIONS)
+		return NULL;
+
+	ms = __nr_to_section(nr);
+	if (!online_section(ms))
+		return NULL;
+
+	/*
+	 * Save some code text when online_section() +
+	 * pfn_section_valid() are sufficient.
+	 */
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) && !pfn_valid(pfn))
+		return NULL;
+
+	if (!pfn_section_valid(ms, pfn))
+		return NULL;
 
-	if (nr < NR_MEM_SECTIONS && online_section_nr(nr) &&
-	    pfn_valid_within(pfn))
-		return pfn_to_page(pfn);
-	return NULL;
+	return pfn_to_page(pfn);
 }
 EXPORT_SYMBOL_GPL(pfn_to_online_page);
 

Powered by blists - more mailing lists