* [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages
@ 2019-08-09 1:08 miles.chen
[not found] ` <20190809010837.24166-1-miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: miles.chen @ 2019-08-09 1:08 UTC (permalink / raw)
To: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim,
Andrew Morton
Cc: linux-mm, linux-kernel, linux-mediatek, wsd_upstream, Miles Chen,
Tobin C . Harding, Kees Cook
From: Miles Chen <miles.chen@mediatek.com>
This RFC patch is sent to discuss the printing address with %p issue.
Since commit ad67b74d2469d9b8 ("printk: hash addresses printed with %p"),
%p gives obfuscated addresses now. When CONFIG_SLUB_DEBUG=y, it is still
useful to get real virtual addresses.
Possible approaches are:
1. stop printing kernel addresses
2. print with %pK,
3. print with %px.
4. do nothing
This patch takes %px approach and shows the output here.
(%px will causes checkpatch warnings, let us ignore the warning here to
have the discussion). Also, use DUMP_PREFIX_OFFSET instead of
DUMP_PREFIX_ADDRESS.
Before this patch:
INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____)
INFO: Object 0x(____ptrval____) @offset=1408 fp=0x(____ptrval____)
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5
Redzone (____ptrval____): bb bb bb bb bb bb bb bb
Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
...
FIX kmalloc-128: Object at 0x(____ptrval____) not freed
After this patch:
INFO: Slab 0xffffffbf00f57000 objects=25 used=23 fp=0xffffffc03d5c3500
INFO: Object 0xffffffc03d5c3500 @offset=13568 fp=0xffffffc03d5c0800
Redzone 00000000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000020: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000030: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000040: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000050: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000060: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Redzone 00000070: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
Object 00000000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000040: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000050: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000060: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
Object 00000070: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5
Redzone 00000000: bb bb bb bb bb bb bb bb
Padding 00000000: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
Padding 00000010: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
Padding 00000020: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
Padding 00000030: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
...
FIX kmalloc-128: Object at 0xffffffc03d5c3500 not freed
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tobin C. Harding <me@tobin.cc>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
---
mm/slub.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 8834563cdb4b..bc1fb8e81557 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -528,7 +528,7 @@ static void print_section(char *level, char *text, u8 *addr,
unsigned int length)
{
metadata_access_enable();
- print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
+ print_hex_dump(level, text, DUMP_PREFIX_OFFSET, 16, 1, addr,
length, 1);
metadata_access_disable();
}
@@ -611,7 +611,7 @@ static void print_tracking(struct kmem_cache *s, void *object)
static void print_page_info(struct page *page)
{
- pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n",
+ pr_err("INFO: Slab 0x%px objects=%u used=%u fp=0x%px flags=0x%04lx\n",
page, page->objects, page->inuse, page->freelist, page->flags);
}
@@ -653,7 +653,7 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
print_page_info(page);
- pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
+ pr_err("INFO: Object 0x%px @offset=%tu fp=0x%px\n\n",
p, p - addr, get_freepointer(s, p));
if (s->flags & SLAB_RED_ZONE)
@@ -991,7 +991,7 @@ static void trace(struct kmem_cache *s, struct page *page, void *object,
int alloc)
{
if (s->flags & SLAB_TRACE) {
- pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
+ pr_info("TRACE %s %s 0x%px inuse=%d fp=0x%p\n",
s->name,
alloc ? "alloc" : "free",
object, page->inuse,
@@ -1212,7 +1212,7 @@ static noinline int free_debug_processing(
slab_unlock(page);
spin_unlock_irqrestore(&n->list_lock, flags);
if (!ret)
- slab_fix(s, "Object at 0x%p not freed", object);
+ slab_fix(s, "Object at 0x%px not freed", object);
return ret;
}
@@ -3693,7 +3693,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
for_each_object(p, s, addr, page->objects) {
if (!test_bit(slab_index(p, s, addr), map)) {
- pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr);
+ pr_err("INFO: Object 0x%px @offset=%tu\n", p, p - addr);
print_tracking(s, p);
}
}
--
2.18.0
^ permalink raw reply related [flat|nested] 6+ messages in thread[parent not found: <20190809010837.24166-1-miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>]
* Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages [not found] ` <20190809010837.24166-1-miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> @ 2019-08-09 2:46 ` Matthew Wilcox 2019-08-09 14:11 ` Miles Chen 2019-08-12 13:32 ` Vlastimil Babka 0 siblings, 2 replies; 6+ messages in thread From: Matthew Wilcox @ 2019-08-09 2:46 UTC (permalink / raw) To: miles.chen-NuS5LvNUpcJWk0Htik3J/w Cc: Andrew Morton, wsd_upstream-NuS5LvNUpcJWk0Htik3J/w, Kees Cook, linux-kernel-u79uwXL29TY76Z2rM5mHXA, Pekka Enberg, linux-mm-Bw31MaZKKs3YtjvyW6yDsg, linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, David Rientjes, Christoph Lameter, Joonsoo Kim, Tobin C . Harding On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org wrote: > Possible approaches are: > 1. stop printing kernel addresses > 2. print with %pK, > 3. print with %px. No. The point of obscuring kernel addresses is that if the attacker manages to find a way to get the kernel to spit out some debug messages that we shouldn't leak all this extra information. > 4. do nothing 5. Find something more useful to print. > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) ... you don't have any randomness on your platform? > INFO: Object 0x(____ptrval____) @offset=1408 fp=0x(____ptrval____) > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 > Redzone (____ptrval____): bb bb bb bb bb bb bb bb > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > ... > FIX kmalloc-128: Object at 0x(____ptrval____) not freed But if you have randomness, at least some of these "pointers" are valuable because you can compare them against "pointers" printed by other parts of the kernel. > After this patch: > > INFO: Slab 0xffffffbf00f57000 objects=25 used=23 fp=0xffffffc03d5c3500 > INFO: Object 0xffffffc03d5c3500 @offset=13568 fp=0xffffffc03d5c0800 > Redzone 00000000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000020: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000030: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000040: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000050: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000060: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000070: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Object 00000000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000040: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000050: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000060: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000070: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 > Redzone 00000000: bb bb bb bb bb bb bb bb > Padding 00000000: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding 00000010: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding 00000020: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding 00000030: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > ... > FIX kmalloc-128: Object at 0xffffffc03d5c3500 not freed It looks prettier, but I'm not convinced it's more useful. Unless your platform lacks randomness ... ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages 2019-08-09 2:46 ` Matthew Wilcox @ 2019-08-09 14:11 ` Miles Chen 2019-08-09 14:26 ` Matthew Wilcox 2019-08-12 13:32 ` Vlastimil Babka 1 sibling, 1 reply; 6+ messages in thread From: Miles Chen @ 2019-08-09 14:11 UTC (permalink / raw) To: Matthew Wilcox Cc: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim, Andrew Morton, linux-mm, linux-kernel, linux-mediatek, wsd_upstream, Tobin C . Harding, Kees Cook On Thu, 2019-08-08 at 19:46 -0700, Matthew Wilcox wrote: > On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@mediatek.com wrote: > > Possible approaches are: > > 1. stop printing kernel addresses > > 2. print with %pK, > > 3. print with %px. > > No. The point of obscuring kernel addresses is that if the attacker manages to find a way to get the kernel to spit out some debug messages that we shouldn't > leak all this extra information. got it. > > > 4. do nothing > > 5. Find something more useful to print. agree > > > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) > > ... you don't have any randomness on your platform? We have randomized base on our platforms. > But if you have randomness, at least some of these "pointers" are valuable > because you can compare them against "pointers" printed by other parts > of the kernel. Understood. Keep current %p, do not leak kernel addresses. I'll collect more cases and see if we really need some extra information. (maybe the @offset in current message is enough) thanks for your comments! ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages 2019-08-09 14:11 ` Miles Chen @ 2019-08-09 14:26 ` Matthew Wilcox 2019-08-12 8:24 ` Miles Chen 0 siblings, 1 reply; 6+ messages in thread From: Matthew Wilcox @ 2019-08-09 14:26 UTC (permalink / raw) To: Miles Chen Cc: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim, Andrew Morton, linux-mm, linux-kernel, linux-mediatek, wsd_upstream, Tobin C . Harding, Kees Cook On Fri, Aug 09, 2019 at 10:11:58PM +0800, Miles Chen wrote: > On Thu, 2019-08-08 at 19:46 -0700, Matthew Wilcox wrote: > > On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@mediatek.com wrote: > > > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) > > > > ... you don't have any randomness on your platform? > > We have randomized base on our platforms. Look at initialize_ptr_random(). If you have randomness, then you get a siphash_1u32() of the address. With no randomness, you get this ___ptrval___ string instead. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages 2019-08-09 14:26 ` Matthew Wilcox @ 2019-08-12 8:24 ` Miles Chen 0 siblings, 0 replies; 6+ messages in thread From: Miles Chen @ 2019-08-12 8:24 UTC (permalink / raw) To: Matthew Wilcox Cc: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim, Andrew Morton, linux-mm, linux-kernel, linux-mediatek, wsd_upstream, Tobin C . Harding, Kees Cook On Fri, 2019-08-09 at 07:26 -0700, Matthew Wilcox wrote: > On Fri, Aug 09, 2019 at 10:11:58PM +0800, Miles Chen wrote: > > On Thu, 2019-08-08 at 19:46 -0700, Matthew Wilcox wrote: > > > On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@mediatek.com wrote: > > > > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) > > > > > > ... you don't have any randomness on your platform? > > > > We have randomized base on our platforms. > > Look at initialize_ptr_random(). If you have randomness, then you > get a siphash_1u32() of the address. With no randomness, you get this > ___ptrval___ string instead. > You are right. There is no randomness in this platform. (I ran my test code on Qemu with no randomness) thanks again ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages 2019-08-09 2:46 ` Matthew Wilcox 2019-08-09 14:11 ` Miles Chen @ 2019-08-12 13:32 ` Vlastimil Babka 1 sibling, 0 replies; 6+ messages in thread From: Vlastimil Babka @ 2019-08-12 13:32 UTC (permalink / raw) To: Matthew Wilcox, miles.chen Cc: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim, Andrew Morton, linux-mm, linux-kernel, linux-mediatek, wsd_upstream, Tobin C . Harding, Kees Cook On 8/9/19 4:46 AM, Matthew Wilcox wrote: > On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@mediatek.com wrote: >> Possible approaches are: >> 1. stop printing kernel addresses >> 2. print with %pK, >> 3. print with %px. > > No. The point of obscuring kernel addresses is that if the attacker manages to find a way to get the kernel to spit out some debug messages that we shouldn't > leak all this extra information. On the other hand, while CONFIG_SLUB_DEBUG=y is common, the actual checks and printing happens when the (relatively expensive) checks are actually enabled during boot, i.e. during a debugging session, not production defaults. I can see how knowing the exact address might be useful when e.g. a crash dump is also taken. I would say %pK would be a good fit, if kptr_restrict also had a setting that makes %pK behave like %px (looks like it doesn't), so that setting would be enabled in such a debugging session. >> 4. do nothing > > 5. Find something more useful to print. > >> INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) > > ... you don't have any randomness on your platform? > >> INFO: Object 0x(____ptrval____) @offset=1408 fp=0x(____ptrval____) >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 >> Redzone (____ptrval____): bb bb bb bb bb bb bb bb >> Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> ... >> FIX kmalloc-128: Object at 0x(____ptrval____) not freed > > But if you have randomness, at least some of these "pointers" are valuable > because you can compare them against "pointers" printed by other parts > of the kernel. > >> After this patch: >> >> INFO: Slab 0xffffffbf00f57000 objects=25 used=23 fp=0xffffffc03d5c3500 >> INFO: Object 0xffffffc03d5c3500 @offset=13568 fp=0xffffffc03d5c0800 >> Redzone 00000000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000020: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000030: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000040: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000050: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000060: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Redzone 00000070: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb >> Object 00000000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000040: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000050: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000060: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >> Object 00000070: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 >> Redzone 00000000: bb bb bb bb bb bb bb bb >> Padding 00000000: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> Padding 00000010: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> Padding 00000020: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> Padding 00000030: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >> ... >> FIX kmalloc-128: Object at 0xffffffc03d5c3500 not freed > > It looks prettier, but I'm not convinced it's more useful. Unless your > platform lacks randomness ... > ^ permalink raw reply [flat|nested] 6+ messages in thread
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2019-08-09 1:08 [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages miles.chen
[not found] ` <20190809010837.24166-1-miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
2019-08-09 2:46 ` Matthew Wilcox
2019-08-09 14:11 ` Miles Chen
2019-08-09 14:26 ` Matthew Wilcox
2019-08-12 8:24 ` Miles Chen
2019-08-12 13:32 ` Vlastimil Babka
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