linux-kernel - [PATCH -next] slub: set PG

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-next>] [day] [month] [year] [list]

Date:	Wed, 29 Feb 2012 17:54:34 +0900
From:	Namhyung Kim <namhyung.kim@....com>
To:	Christoph Lameter <cl@...ux-foundation.org>,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>
Cc:	Namhyung Kim <namhyung@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH -next] slub: set PG_slab on all of slab pages

Unlike SLAB, SLUB doesn't set PG_slab on tail pages, so if a user would
call free_pages() incorrectly on a object in a tail page, she will get
confused with the undefined result. Setting the flag would help her by
emitting a warning on bad_page() in such a case.

Reported-by: Sangseok Lee <sangseok.lee@....com>
Signed-off-by: Namhyung Kim <namhyung.kim@....com>
---
 mm/slub.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 33bab2aca882..575baacbec9b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1287,6 +1287,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	struct page *page;
 	struct kmem_cache_order_objects oo = s->oo;
 	gfp_t alloc_gfp;
+	int i;
 
 	flags &= gfp_allowed_mask;
 
@@ -1320,6 +1321,9 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	if (!page)
 		return NULL;
 
+	for (i = 0; i < 1 << oo_order(oo); i++)
+		__SetPageSlab(page + i);
+
 	if (kmemcheck_enabled
 		&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
 		int pages = 1 << oo_order(oo);
@@ -1369,7 +1373,6 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 	inc_slabs_node(s, page_to_nid(page), page->objects);
 	page->slab = s;
-	page->flags |= 1 << PG_slab;
 
 	start = page_address(page);
 
@@ -1396,6 +1399,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
 {
 	int order = compound_order(page);
 	int pages = 1 << order;
+	int i;
 
 	if (kmem_cache_debug(s)) {
 		void *p;
@@ -1413,7 +1417,11 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
 		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
 		-pages);
 
-	__ClearPageSlab(page);
+	for (i = 0; i < pages; i++) {
+		BUG_ON(!PageSlab(page + i));
+		__ClearPageSlab(page + i);
+	}
+
 	reset_page_mapcount(page);
 	if (current->reclaim_state)
 		current->reclaim_state->reclaimed_slab += pages;
-- 
1.7.9

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/