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slab: Fix misplaced __free_one()

PATCH In review Kees Cook 3 participants 3 messages Jun 26, 2020 – Jun 29, 2020

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Kees Cook

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#0 lore raw

PATCH 1/1 slab: Fix misplaced __free_one()

The implementation of __free_one() was accidentally placed inside a CONFIG_NUMA #ifdef. Move it above.

Reported-by Randy Dunlap <[email protected]>
Link https://lore.kernel.org/lkml/[email protected] open here
Signed-off-by Kees Cook <[email protected]>

---
This a fix for slab-add-naive-detection-of-double-free.patch

---
 mm/slab.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)
mm/slab.c +10 -10
index bbff6705ab2b..5ccb151a6e8f 100644
@@ -588,6 +588,16 @@ static int transfer_objects(struct array_cache *to,
 	return nr;
 }
 
+/* &alien->lock must be held by alien callers. */
+static __always_inline void __free_one(struct array_cache *ac, void *objp)
+{
+	/* Avoid trivial double-free. */
+	if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
+	    WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp))
+		return;
+	ac->entry[ac->avail++] = objp;
+}
+
 #ifndef CONFIG_NUMA
 
 #define drain_alien_cache(cachep, alien) do { } while (0)

@@ -749,16 +759,6 @@ static void drain_alien_cache(struct kmem_cache *cachep,
 	}
 }
 
-/* &alien->lock must be held by alien callers. */
-static __always_inline void __free_one(struct array_cache *ac, void *objp)
-{
-	/* Avoid trivial double-free. */
-	if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
-	    WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp))
-		return;
-	ac->entry[ac->avail++] = objp;
-}
-
 static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
 				int node, int page_node)
 {
Signature · 5 lines
2.25.1


-- 
Kees Cook
Acked-by on v1 1/1
#1 lore raw
Quoted 6 lines · Kees Cook

The implementation of __free_one() was accidentally placed inside a CONFIG_NUMA #ifdef. Move it above.

Reported-by Randy Dunlap <[email protected]>
Link https://lore.kernel.org/lkml/[email protected] open here
Signed-off-by Kees Cook <[email protected]>
Acked-by Randy Dunlap <[email protected]> # build-tested

Thanks.

Quoted 45 lines

---
This a fix for slab-add-naive-detection-of-double-free.patch

---
 mm/slab.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)
mm/slab.c +10 -10
index bbff6705ab2b..5ccb151a6e8f 100644
@@ -588,6 +588,16 @@ static int transfer_objects(struct array_cache *to,
 	return nr;
 }
 
+/* &alien->lock must be held by alien callers. */
+static __always_inline void __free_one(struct array_cache *ac, void *objp)
+{
+	/* Avoid trivial double-free. */
+	if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
+	    WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp))
+		return;
+	ac->entry[ac->avail++] = objp;
+}
+
 #ifndef CONFIG_NUMA
 
 #define drain_alien_cache(cachep, alien) do { } while (0)

@@ -749,16 +759,6 @@ static void drain_alien_cache(struct kmem_cache *cachep,
 	}
 }
 
-/* &alien->lock must be held by alien callers. */
-static __always_inline void __free_one(struct array_cache *ac, void *objp)
-{
-	/* Avoid trivial double-free. */
-	if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
-	    WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp))
-		return;
-	ac->entry[ac->avail++] = objp;
-}
-
 static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
 				int node, int page_node)
 {
Signature · 1 line
~Randy
#2 lore raw
In reply to Kees Cook

Hi Kees,

Quoted 7 lines · On Fri, 26 Jun 2020 13:07:53 -0700 Kees Cook <[email protected]> wrote:

The implementation of __free_one() was accidentally placed inside a CONFIG_NUMA #ifdef. Move it above.

Reported-by Randy Dunlap <[email protected]>
Link https://lore.kernel.org/lkml/[email protected] open here
Signed-off-by Kees Cook <[email protected]>

I added that to linux-next for today.

Signature · 2 lines
Cheers,
Stephen Rothwell