[PATCH] mm/slub: Avoid recursive loop with kmemleak

[PATCH] mm/slub: Avoid recursive loop with kmemleak

[Kees Cook]

The system will immediate fill up stack and crash when both
CONFIG_DEBUG_KMEMLEAK and CONFIG_MEM_ALLOC_PROFILING are enabled.
Avoid allocation tagging of kmemleak caches, otherwise recursive
allocation tracking occurs.

Fixes: 279bb991b4d9 ("mm/slab: add allocation accounting into slab allocation and free paths")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: linux-mm@kvack.org
---
 mm/kmemleak.c | 4 ++--
 mm/slub.c     | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index c55c2cbb6837..fdcf01f62202 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -463,7 +463,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
 
 	/* try the slab allocator first */
 	if (object_cache) {
-		object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
+		object = kmem_cache_alloc_noprof(object_cache, gfp_kmemleak_mask(gfp));
 		if (object)
 			return object;
 	}
@@ -947,7 +947,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
 	untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
 
 	if (scan_area_cache)
-		area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
+		area = kmem_cache_alloc_noprof(scan_area_cache, gfp_kmemleak_mask(gfp));
 
 	raw_spin_lock_irqsave(&object->lock, flags);
 	if (!area) {
diff --git a/mm/slub.c b/mm/slub.c
index a94a0507e19c..9ae032ed17ed 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2016,7 +2016,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
 	if (!p)
 		return NULL;
 
-	if (s->flags & SLAB_NO_OBJ_EXT)
+	if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE))
 		return NULL;
 
 	if (flags & __GFP_NO_OBJ_EXT)
-- 
2.34.1

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Kent Overstreet]

On Thu, Apr 25, 2024 at 01:55:23PM -0700, Kees Cook wrote:
> The system will immediate fill up stack and crash when both
> CONFIG_DEBUG_KMEMLEAK and CONFIG_MEM_ALLOC_PROFILING are enabled.
> Avoid allocation tagging of kmemleak caches, otherwise recursive
> allocation tracking occurs.
> 
> Fixes: 279bb991b4d9 ("mm/slab: add allocation accounting into slab allocation and free paths")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> Cc: Suren Baghdasaryan <surenb@google.com>
> Cc: Kent Overstreet <kent.overstreet@linux.dev>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> 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: Vlastimil Babka <vbabka@suse.cz>
> Cc: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Cc: linux-mm@kvack.org
> ---
>  mm/kmemleak.c | 4 ++--
>  mm/slub.c     | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index c55c2cbb6837..fdcf01f62202 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -463,7 +463,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
>  
>  	/* try the slab allocator first */
>  	if (object_cache) {
> -		object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
> +		object = kmem_cache_alloc_noprof(object_cache, gfp_kmemleak_mask(gfp));

What do these get accounted to, or does this now pop a warning with
CONFIG_MEM_ALLOC_PROFILING_DEBUG?

>  		if (object)
>  			return object;
>  	}
> @@ -947,7 +947,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
>  	untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
>  
>  	if (scan_area_cache)
> -		area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
> +		area = kmem_cache_alloc_noprof(scan_area_cache, gfp_kmemleak_mask(gfp));
>  
>  	raw_spin_lock_irqsave(&object->lock, flags);
>  	if (!area) {
> diff --git a/mm/slub.c b/mm/slub.c
> index a94a0507e19c..9ae032ed17ed 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2016,7 +2016,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
>  	if (!p)
>  		return NULL;
>  
> -	if (s->flags & SLAB_NO_OBJ_EXT)
> +	if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE))
>  		return NULL;
>  
>  	if (flags & __GFP_NO_OBJ_EXT)
> -- 
> 2.34.1
> 

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Suren Baghdasaryan]

On Thu, Apr 25, 2024 at 2:09 PM Kent Overstreet
<kent.overstreet@linux.dev> wrote:
>
> On Thu, Apr 25, 2024 at 01:55:23PM -0700, Kees Cook wrote:
> > The system will immediate fill up stack and crash when both
> > CONFIG_DEBUG_KMEMLEAK and CONFIG_MEM_ALLOC_PROFILING are enabled.
> > Avoid allocation tagging of kmemleak caches, otherwise recursive
> > allocation tracking occurs.
> >
> > Fixes: 279bb991b4d9 ("mm/slab: add allocation accounting into slab allocation and free paths")
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> > Cc: Suren Baghdasaryan <surenb@google.com>
> > Cc: Kent Overstreet <kent.overstreet@linux.dev>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > 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: Vlastimil Babka <vbabka@suse.cz>
> > Cc: Roman Gushchin <roman.gushchin@linux.dev>
> > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> > Cc: linux-mm@kvack.org
> > ---
> >  mm/kmemleak.c | 4 ++--
> >  mm/slub.c     | 2 +-
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> > index c55c2cbb6837..fdcf01f62202 100644
> > --- a/mm/kmemleak.c
> > +++ b/mm/kmemleak.c
> > @@ -463,7 +463,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
> >
> >       /* try the slab allocator first */
> >       if (object_cache) {
> > -             object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
> > +             object = kmem_cache_alloc_noprof(object_cache, gfp_kmemleak_mask(gfp));
>
> What do these get accounted to, or does this now pop a warning with
> CONFIG_MEM_ALLOC_PROFILING_DEBUG?

Thanks for the fix, Kees!
I'll look into this recursion more closely to see if there is a better
way to break it. As a stopgap measure seems ok to me. I also think
it's unlikely that one would use both tracking mechanisms on the same
system.

>
> >               if (object)
> >                       return object;
> >       }
> > @@ -947,7 +947,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
> >       untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
> >
> >       if (scan_area_cache)
> > -             area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
> > +             area = kmem_cache_alloc_noprof(scan_area_cache, gfp_kmemleak_mask(gfp));
> >
> >       raw_spin_lock_irqsave(&object->lock, flags);
> >       if (!area) {
> > diff --git a/mm/slub.c b/mm/slub.c
> > index a94a0507e19c..9ae032ed17ed 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -2016,7 +2016,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
> >       if (!p)
> >               return NULL;
> >
> > -     if (s->flags & SLAB_NO_OBJ_EXT)
> > +     if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE))
> >               return NULL;
> >
> >       if (flags & __GFP_NO_OBJ_EXT)
> > --
> > 2.34.1
> >

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Andrew Morton]

On Thu, 25 Apr 2024 14:30:55 -0700 Suren Baghdasaryan <surenb@google.com> wrote:

> > > --- a/mm/kmemleak.c
> > > +++ b/mm/kmemleak.c
> > > @@ -463,7 +463,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
> > >
> > >       /* try the slab allocator first */
> > >       if (object_cache) {
> > > -             object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
> > > +             object = kmem_cache_alloc_noprof(object_cache, gfp_kmemleak_mask(gfp));
> >
> > What do these get accounted to, or does this now pop a warning with
> > CONFIG_MEM_ALLOC_PROFILING_DEBUG?
> 
> Thanks for the fix, Kees!
> I'll look into this recursion more closely to see if there is a better
> way to break it. As a stopgap measure seems ok to me. I also think
> it's unlikely that one would use both tracking mechanisms on the same
> system.

I'd really like to start building mm-stable without having to route
around memprofiling.  How about I include Kees's patch in that for now?

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Kent Overstreet]

On Thu, Apr 25, 2024 at 04:49:17PM -0700, Andrew Morton wrote:
> On Thu, 25 Apr 2024 14:30:55 -0700 Suren Baghdasaryan <surenb@google.com> wrote:
> 
> > > > --- a/mm/kmemleak.c
> > > > +++ b/mm/kmemleak.c
> > > > @@ -463,7 +463,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
> > > >
> > > >       /* try the slab allocator first */
> > > >       if (object_cache) {
> > > > -             object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
> > > > +             object = kmem_cache_alloc_noprof(object_cache, gfp_kmemleak_mask(gfp));
> > >
> > > What do these get accounted to, or does this now pop a warning with
> > > CONFIG_MEM_ALLOC_PROFILING_DEBUG?
> > 
> > Thanks for the fix, Kees!
> > I'll look into this recursion more closely to see if there is a better
> > way to break it. As a stopgap measure seems ok to me. I also think
> > it's unlikely that one would use both tracking mechanisms on the same
> > system.
> 
> I'd really like to start building mm-stable without having to route
> around memprofiling.  How about I include Kees's patch in that for now?

Agreed

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Suren Baghdasaryan]

On Thu, Apr 25, 2024 at 5:19 PM Kent Overstreet
<kent.overstreet@linux.dev> wrote:
>
> On Thu, Apr 25, 2024 at 04:49:17PM -0700, Andrew Morton wrote:
> > On Thu, 25 Apr 2024 14:30:55 -0700 Suren Baghdasaryan <surenb@google.com> wrote:
> >
> > > > > --- a/mm/kmemleak.c
> > > > > +++ b/mm/kmemleak.c
> > > > > @@ -463,7 +463,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
> > > > >
> > > > >       /* try the slab allocator first */
> > > > >       if (object_cache) {
> > > > > -             object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
> > > > > +             object = kmem_cache_alloc_noprof(object_cache, gfp_kmemleak_mask(gfp));
> > > >
> > > > What do these get accounted to, or does this now pop a warning with
> > > > CONFIG_MEM_ALLOC_PROFILING_DEBUG?
> > >
> > > Thanks for the fix, Kees!
> > > I'll look into this recursion more closely to see if there is a better
> > > way to break it. As a stopgap measure seems ok to me. I also think
> > > it's unlikely that one would use both tracking mechanisms on the same
> > > system.
> >
> > I'd really like to start building mm-stable without having to route
> > around memprofiling.  How about I include Kees's patch in that for now?
>
> Agreed

Yes, please. When I figure out a better way, I'll post a separate patch. Thanks!

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Catalin Marinas]

On Thu, Apr 25, 2024 at 01:55:23PM -0700, Kees Cook wrote:
> The system will immediate fill up stack and crash when both
> CONFIG_DEBUG_KMEMLEAK and CONFIG_MEM_ALLOC_PROFILING are enabled.
> Avoid allocation tagging of kmemleak caches, otherwise recursive
> allocation tracking occurs.
> 
> Fixes: 279bb991b4d9 ("mm/slab: add allocation accounting into slab allocation and free paths")
> Signed-off-by: Kees Cook <keescook@chromium.org>

For the kmemleak bits:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH] mm/slub: Avoid recursive loop with kmemleak

[Kees Cook]

On Fri, Apr 26, 2024 at 03:52:24PM +0100, Catalin Marinas wrote:
> On Thu, Apr 25, 2024 at 01:55:23PM -0700, Kees Cook wrote:
> > The system will immediate fill up stack and crash when both

Oops, typo from me: "immediately". You'd never guess I'm a native English
speaker! :)

> > CONFIG_DEBUG_KMEMLEAK and CONFIG_MEM_ALLOC_PROFILING are enabled.
> > Avoid allocation tagging of kmemleak caches, otherwise recursive
> > allocation tracking occurs.
> > 
> > Fixes: 279bb991b4d9 ("mm/slab: add allocation accounting into slab allocation and free paths")
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> For the kmemleak bits:
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks!

-Kees

-- 
Kees Cook