The patch titled
Increase slab redzone to 64bits
has been added to the -mm tree. Its filename is
increase-slab-redzone-to-64bits.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Increase slab redzone to 64bits
From: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
There are two problems with the existing redzone implementation.
Firstly, it's causing misalignment of structures which contain a 64-bit
integer, such as netfilter's 'struct ipt_entry' -- causing netfilter
modules to fail to load because of the misalignment. (In particular, the
first check in
net/ipv4/netfilter/ip_tables.c::check_entry_size_and_hooks())
I considered just fixing this by setting ARCH_KMALLOC_MINALIGN to
__alignof__(uint64_t) in the default case where the architecture hasn't
already set it -- but that would disable redzone checks on those
architectures.
When investigating this, I noticed that on 64-bit platforms we're using a
32-bit value of RED_ACTIVE/RED_INACTIVE in the 64-bit memory location set
aside for the redzone. Which means that the four bytes immediately before
or after the allocated object at 0x00,0x00,0x00,0x00 for LE and BE
machines, respectively. Which is probably not the most useful choice of
poison value.
One way to fix both of those at once is just to switch to 64-bit
redzones in all cases.
Signed-off-by: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/poison.h | 4 ++--
mm/slab.c | 39 ++++++++++++++++++++-------------------
2 files changed, 22 insertions(+), 21 deletions(-)
diff -puN include/linux/poison.h~increase-slab-redzone-to-64bits include/linux/poison.h
--- a/include/linux/poison.h~increase-slab-redzone-to-64bits
+++ a/include/linux/poison.h
@@ -15,8 +15,8 @@
* Magic nums for obj red zoning.
* Placed in the first word before and the first word after an obj.
*/
-#define RED_INACTIVE 0x5A2CF071UL /* when obj is inactive */
-#define RED_ACTIVE 0x170FC2A5UL /* when obj is active */
+#define RED_INACTIVE 0x5A2CF0715A2CF071ULL /* when obj is inactive */
+#define RED_ACTIVE 0x170FC2A5170FC2A5ULL /* when obj is active */
#define SLUB_RED_INACTIVE 0xbb
#define SLUB_RED_ACTIVE 0xcc
diff -puN mm/slab.c~increase-slab-redzone-to-64bits mm/slab.c
--- a/mm/slab.c~increase-slab-redzone-to-64bits
+++ a/mm/slab.c
@@ -148,10 +148,11 @@
* Usually, the kmalloc caches are cache_line_size() aligned, except when
* DEBUG and FORCED_DEBUG are enabled, then they are BYTES_PER_WORD aligned.
* Some archs want to perform DMA into kmalloc caches and need a guaranteed
- * alignment larger than BYTES_PER_WORD. ARCH_KMALLOC_MINALIGN allows that.
- * Note that this flag disables some debug features.
+ * alignment larger than the alignment of a uint64_t. ARCH_KMALLOC_MINALIGN
+ * allows that.
+ * Note that increasing this value may disable some debug features.
*/
-#define ARCH_KMALLOC_MINALIGN 0
+#define ARCH_KMALLOC_MINALIGN __alignof__(uint64_t)
#endif
#ifndef ARCH_SLAB_MINALIGN
@@ -536,19 +537,19 @@ static int obj_size(struct kmem_cache *c
return cachep->obj_size;
}
-static unsigned long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
+static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
{
BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
- return (unsigned long*) (objp+obj_offset(cachep)-BYTES_PER_WORD);
+ return (unsigned long long*) (objp+obj_offset(cachep)-8);
}
-static unsigned long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
+static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
{
BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
if (cachep->flags & SLAB_STORE_USER)
- return (unsigned long *)(objp + cachep->buffer_size -
- 2 * BYTES_PER_WORD);
- return (unsigned long *)(objp + cachep->buffer_size - BYTES_PER_WORD);
+ return (unsigned long long *)(objp + cachep->buffer_size - 8 -
+ BYTES_PER_WORD);
+ return (unsigned long long *) (objp + cachep->buffer_size - 8);
}
static void **dbg_userword(struct kmem_cache *cachep, void *objp)
@@ -561,8 +562,8 @@ static void **dbg_userword(struct kmem_c
#define obj_offset(x) 0
#define obj_size(cachep) (cachep->buffer_size)
-#define dbg_redzone1(cachep, objp) ({BUG(); (unsigned long *)NULL;})
-#define dbg_redzone2(cachep, objp) ({BUG(); (unsigned long *)NULL;})
+#define dbg_redzone1(cachep, objp) ({BUG(); (unsigned long long *)NULL;})
+#define dbg_redzone2(cachep, objp) ({BUG(); (unsigned long long *)NULL;})
#define dbg_userword(cachep, objp) ({BUG(); (void **)NULL;})
#endif
@@ -1776,7 +1777,7 @@ static void print_objinfo(struct kmem_ca
char *realobj;
if (cachep->flags & SLAB_RED_ZONE) {
- printk(KERN_ERR "Redzone: 0x%lx/0x%lx.\n",
+ printk(KERN_ERR "Redzone: 0x%llx/0x%llx.\n",
*dbg_redzone1(cachep, objp),
*dbg_redzone2(cachep, objp));
}
@@ -2239,7 +2240,7 @@ kmem_cache_create (const char *name, siz
* is greater than BYTES_PER_WORD.
*/
if (flags & SLAB_RED_ZONE || flags & SLAB_STORE_USER)
- ralign = BYTES_PER_WORD;
+ ralign = __alignof__(unsigned long long);
/* 2) arch mandated alignment */
if (ralign < ARCH_SLAB_MINALIGN) {
@@ -2250,7 +2251,7 @@ kmem_cache_create (const char *name, siz
ralign = align;
}
/* disable debug if necessary */
- if (ralign > BYTES_PER_WORD)
+ if (ralign > __alignof__(unsigned long long))
flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
/*
* 4) Store it.
@@ -2271,8 +2272,8 @@ kmem_cache_create (const char *name, siz
*/
if (flags & SLAB_RED_ZONE) {
/* add space for red zone words */
- cachep->obj_offset += BYTES_PER_WORD;
- size += 2 * BYTES_PER_WORD;
+ cachep->obj_offset += sizeof(unsigned long long);
+ size += 2 * sizeof(unsigned long long);
}
if (flags & SLAB_STORE_USER) {
/* user store requires one word storage behind the end of
@@ -2833,7 +2834,7 @@ static void kfree_debugcheck(const void
static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
{
- unsigned long redzone1, redzone2;
+ unsigned long long redzone1, redzone2;
redzone1 = *dbg_redzone1(cache, obj);
redzone2 = *dbg_redzone2(cache, obj);
@@ -2849,7 +2850,7 @@ static inline void verify_redzone_free(s
else
slab_error(cache, "memory outside object was overwritten");
- printk(KERN_ERR "%p: redzone 1:0x%lx, redzone 2:0x%lx.\n",
+ printk(KERN_ERR "%p: redzone 1:0x%llx, redzone 2:0x%llx.\n",
obj, redzone1, redzone2);
}
@@ -3065,7 +3066,7 @@ static void *cache_alloc_debugcheck_afte
slab_error(cachep, "double free, or memory outside"
" object was overwritten");
printk(KERN_ERR
- "%p: redzone 1:0x%lx, redzone 2:0x%lx\n",
+ "%p: redzone 1:0x%llx, redzone 2:0x%llx\n",
objp, *dbg_redzone1(cachep, objp),
*dbg_redzone2(cachep, objp));
}
_
Patches currently in -mm which might be from dwmw2@xxxxxxxxxxxxx are
origin.patch
git-kbuild.patch
dont-force-uclinux-mtd-map-to-be-root-dev.patch
block2mtd_paramline-mustnt-be-__initdata.patch
git-battery.patch
increase-slab-redzone-to-64bits.patch
increase-slab-redzone-to-64bits-fix.patch
add-ability-to-keep-track-of-callers-of-symbol_getput.patch
update-mtd-use-of-symbol_getput.patch
update-dvb-use-of-symbol_getput.patch
clean-up-mutex_trylock-noise.patch
rename-get_property-to-of_get_property-drivers.patch
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