RE: [PATCH 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()
> -Original Message-
> From: Kirill A. Shutemov
> Sent: Tuesday, 10 September 2019 8:15 PM
> To: Alastair D'Silva
> Cc: alast...@d-silva.org; Andrew Morton ;
> David Hildenbrand ; Oscar Salvador
> ; Michal Hocko ; Pavel Tatashin
> ; Wei Yang ;
> Dan Williams ; Qian Cai ; Jason
> Gunthorpe ; Logan Gunthorpe ; Ira
> Weiny ; linux...@kvack.org; linux-
> ker...@vger.kernel.org
> Subject: Re: [PATCH 1/2] memory_hotplug: Add a bounds check to
> check_hotplug_memory_range()
>
> On Tue, Sep 10, 2019 at 12:52:20PM +1000, Alastair D'Silva wrote:
> > From: Alastair D'Silva
> >
> > On PowerPC, the address ranges allocated to OpenCAPI LPC memory are
> > allocated from firmware. These address ranges may be higher than what
> > older kernels permit, as we increased the maximum permissable address
> > in commit 4ffe713b7587
> > ("powerpc/mm: Increase the max addressable memory to 2PB"). It is
> > possible that the addressable range may change again in the future.
> >
> > In this scenario, we end up with a bogus section returned from
> > __section_nr (see the discussion on the thread "mm: Trigger bug on if
> > a section is not found in __section_nr").
> >
> > Adding a check here means that we fail early and have an opportunity
> > to handle the error gracefully, rather than rumbling on and
> > potentially accessing an incorrect section.
> >
> > Further discussion is also on the thread ("powerpc: Perform a bounds
> > check in arch_add_memory").
> >
> > Signed-off-by: Alastair D'Silva
> > ---
> > include/linux/memory_hotplug.h | 1 +
> > mm/memory_hotplug.c| 19 ++-
> > 2 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/memory_hotplug.h
> > b/include/linux/memory_hotplug.h index f46ea71b4ffd..bc477e98a310
> > 100644
> > --- a/include/linux/memory_hotplug.h
> > +++ b/include/linux/memory_hotplug.h
> > @@ -110,6 +110,7 @@ extern void
> > __online_page_increment_counters(struct page *page); extern void
> > __online_page_free(struct page *page);
> >
> > extern int try_online_node(int nid);
> > +int check_hotplug_memory_addressable(u64 start, u64 size);
> >
> > extern int arch_add_memory(int nid, u64 start, u64 size,
> > struct mhp_restrictions *restrictions); diff --git
> > a/mm/memory_hotplug.c b/mm/memory_hotplug.c index
> > c73f09913165..3c5428b014f9 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1030,6 +1030,23 @@ int try_online_node(int nid)
> > return ret;
> > }
> >
> > +#ifndef MAX_POSSIBLE_PHYSMEM_BITS
> > +#ifdef MAX_PHYSMEM_BITS
> > +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS #endif
> #endif
> > +
> > +int check_hotplug_memory_addressable(u64 start, u64 size) { #ifdef
> > +MAX_POSSIBLE_PHYSMEM_BITS
>
> How can it be not defined? You've defined it 6 lines above.
>
It's only conditionally defined.
I'll be following David H's advice and just using MAX_PHYSMEM_BITS in the
next spin anyway.
> > + if ((start + size - 1) >> MAX_POSSIBLE_PHYSMEM_BITS)
> > + return -E2BIG;
> > +#endif
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(check_hotplug_memory_addressable);
> > +
> > static int check_hotplug_memory_range(u64 start, u64 size) {
> > /* memory range must be block size aligned */ @@ -1040,7 +1057,7
> @@
> > static int check_hotplug_memory_range(u64 start, u64 size)
> > return -EINVAL;
> > }
> >
> > - return 0;
> > + return check_hotplug_memory_addressable(start, size);
> > }
> >
> > static int online_memory_block(struct memory_block *mem, void *arg)
> > --
> > 2.21.0
> >
>
> --
> Kirill A. Shutemov
>
--
Alastair D'Silva mob: 0423 762 819
skype: alastair_dsilva msn: alast...@d-silva.org
blog: http://alastair.d-silva.orgTwitter: @EvilDeece
RE: [PATCH 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()
> -Original Message-
> From: David Hildenbrand
> Sent: Tuesday, 10 September 2019 5:46 PM
> To: Alastair D'Silva ; alast...@d-silva.org
> Cc: Andrew Morton ; Oscar Salvador
> ; Michal Hocko ; Pavel Tatashin
> ; Wei Yang ;
> Dan Williams ; Qian Cai ; Jason
> Gunthorpe ; Logan Gunthorpe ; Ira
> Weiny ; linux...@kvack.org; linux-
> ker...@vger.kernel.org
> Subject: Re: [PATCH 1/2] memory_hotplug: Add a bounds check to
> check_hotplug_memory_range()
>
> On 10.09.19 04:52, Alastair D'Silva wrote:
> > From: Alastair D'Silva
> >
> > On PowerPC, the address ranges allocated to OpenCAPI LPC memory are
> > allocated from firmware. These address ranges may be higher than what
> > older kernels permit, as we increased the maximum permissable address
> > in commit 4ffe713b7587
> > ("powerpc/mm: Increase the max addressable memory to 2PB"). It is
> > possible that the addressable range may change again in the future.
> >
> > In this scenario, we end up with a bogus section returned from
> > __section_nr (see the discussion on the thread "mm: Trigger bug on if
> > a section is not found in __section_nr").
> >
> > Adding a check here means that we fail early and have an opportunity
> > to handle the error gracefully, rather than rumbling on and
> > potentially accessing an incorrect section.
> >
> > Further discussion is also on the thread ("powerpc: Perform a bounds
> > check in arch_add_memory").
> >
> > Signed-off-by: Alastair D'Silva
> > ---
> > include/linux/memory_hotplug.h | 1 +
> > mm/memory_hotplug.c| 19 ++-
> > 2 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/memory_hotplug.h
> > b/include/linux/memory_hotplug.h index f46ea71b4ffd..bc477e98a310
> > 100644
> > --- a/include/linux/memory_hotplug.h
> > +++ b/include/linux/memory_hotplug.h
> > @@ -110,6 +110,7 @@ extern void
> > __online_page_increment_counters(struct page *page); extern void
> > __online_page_free(struct page *page);
> >
> > extern int try_online_node(int nid);
> > +int check_hotplug_memory_addressable(u64 start, u64 size);
> >
> > extern int arch_add_memory(int nid, u64 start, u64 size,
> > struct mhp_restrictions *restrictions); diff --git
> > a/mm/memory_hotplug.c b/mm/memory_hotplug.c index
> > c73f09913165..3c5428b014f9 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1030,6 +1030,23 @@ int try_online_node(int nid)
> > return ret;
> > }
> >
> > +#ifndef MAX_POSSIBLE_PHYSMEM_BITS
> > +#ifdef MAX_PHYSMEM_BITS
> > +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS #endif
> #endif
> > +
>
> I think using MAX_POSSIBLE_PHYSMEM_BITS bits is wrong. You should use
> MAX_PHYSMEM_BITS.
>
> E.g. on x86_64, MAX_POSSIBLE_PHYSMEM_BITS is 52, while
> MAX_PHYSMEM_BITS is (pgtable_l5_enabled() ? 52 : 46) - so
> MAX_PHYSMEM_BITS depends on the actual HW.
>
Thanks, I was following the pattern from zsmalloc.c, but what you say makes
sense.
> > +int check_hotplug_memory_addressable(u64 start, u64 size) { #ifdef
> > +MAX_POSSIBLE_PHYSMEM_BITS
> > + if ((start + size - 1) >> MAX_POSSIBLE_PHYSMEM_BITS)
> > + return -E2BIG;
> > +#endif
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(check_hotplug_memory_addressable);
> > +
> > static int check_hotplug_memory_range(u64 start, u64 size) {
> > /* memory range must be block size aligned */ @@ -1040,7 +1057,7
> @@
> > static int check_hotplug_memory_range(u64 start, u64 size)
> > return -EINVAL;
> > }
> >
> > - return 0;
> > + return check_hotplug_memory_addressable(start, size);
> > }
> >
> > static int online_memory_block(struct memory_block *mem, void *arg)
> >
>
>
> --
>
> Thanks,
>
> David / dhildenb
>
--
Alastair D'Silva mob: 0423 762 819
skype: alastair_dsilva msn: alast...@d-silva.org
blog: http://alastair.d-silva.orgTwitter: @EvilDeece
Re: [PATCH 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()
On Tue, Sep 10, 2019 at 12:52:20PM +1000, Alastair D'Silva wrote:
> From: Alastair D'Silva
>
> On PowerPC, the address ranges allocated to OpenCAPI LPC memory
> are allocated from firmware. These address ranges may be higher
> than what older kernels permit, as we increased the maximum
> permissable address in commit 4ffe713b7587
> ("powerpc/mm: Increase the max addressable memory to 2PB"). It is
> possible that the addressable range may change again in the
> future.
>
> In this scenario, we end up with a bogus section returned from
> __section_nr (see the discussion on the thread "mm: Trigger bug on
> if a section is not found in __section_nr").
>
> Adding a check here means that we fail early and have an
> opportunity to handle the error gracefully, rather than rumbling
> on and potentially accessing an incorrect section.
>
> Further discussion is also on the thread ("powerpc: Perform a bounds
> check in arch_add_memory").
>
> Signed-off-by: Alastair D'Silva
> ---
> include/linux/memory_hotplug.h | 1 +
> mm/memory_hotplug.c| 19 ++-
> 2 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index f46ea71b4ffd..bc477e98a310 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -110,6 +110,7 @@ extern void __online_page_increment_counters(struct page
> *page);
> extern void __online_page_free(struct page *page);
>
> extern int try_online_node(int nid);
> +int check_hotplug_memory_addressable(u64 start, u64 size);
>
> extern int arch_add_memory(int nid, u64 start, u64 size,
> struct mhp_restrictions *restrictions);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index c73f09913165..3c5428b014f9 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1030,6 +1030,23 @@ int try_online_node(int nid)
> return ret;
> }
>
> +#ifndef MAX_POSSIBLE_PHYSMEM_BITS
> +#ifdef MAX_PHYSMEM_BITS
> +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
> +#endif
> +#endif
> +
> +int check_hotplug_memory_addressable(u64 start, u64 size)
> +{
> +#ifdef MAX_POSSIBLE_PHYSMEM_BITS
How can it be not defined? You've defined it 6 lines above.
> + if ((start + size - 1) >> MAX_POSSIBLE_PHYSMEM_BITS)
> + return -E2BIG;
> +#endif
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(check_hotplug_memory_addressable);
> +
> static int check_hotplug_memory_range(u64 start, u64 size)
> {
> /* memory range must be block size aligned */
> @@ -1040,7 +1057,7 @@ static int check_hotplug_memory_range(u64 start, u64
> size)
> return -EINVAL;
> }
>
> - return 0;
> + return check_hotplug_memory_addressable(start, size);
> }
>
> static int online_memory_block(struct memory_block *mem, void *arg)
> --
> 2.21.0
>
--
Kirill A. Shutemov
Re: [PATCH 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()
On 10.09.19 04:52, Alastair D'Silva wrote:
> From: Alastair D'Silva
>
> On PowerPC, the address ranges allocated to OpenCAPI LPC memory
> are allocated from firmware. These address ranges may be higher
> than what older kernels permit, as we increased the maximum
> permissable address in commit 4ffe713b7587
> ("powerpc/mm: Increase the max addressable memory to 2PB"). It is
> possible that the addressable range may change again in the
> future.
>
> In this scenario, we end up with a bogus section returned from
> __section_nr (see the discussion on the thread "mm: Trigger bug on
> if a section is not found in __section_nr").
>
> Adding a check here means that we fail early and have an
> opportunity to handle the error gracefully, rather than rumbling
> on and potentially accessing an incorrect section.
>
> Further discussion is also on the thread ("powerpc: Perform a bounds
> check in arch_add_memory").
>
> Signed-off-by: Alastair D'Silva
> ---
> include/linux/memory_hotplug.h | 1 +
> mm/memory_hotplug.c| 19 ++-
> 2 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index f46ea71b4ffd..bc477e98a310 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -110,6 +110,7 @@ extern void __online_page_increment_counters(struct page
> *page);
> extern void __online_page_free(struct page *page);
>
> extern int try_online_node(int nid);
> +int check_hotplug_memory_addressable(u64 start, u64 size);
>
> extern int arch_add_memory(int nid, u64 start, u64 size,
> struct mhp_restrictions *restrictions);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index c73f09913165..3c5428b014f9 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1030,6 +1030,23 @@ int try_online_node(int nid)
> return ret;
> }
>
> +#ifndef MAX_POSSIBLE_PHYSMEM_BITS
> +#ifdef MAX_PHYSMEM_BITS
> +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
> +#endif
> +#endif
> +
I think using MAX_POSSIBLE_PHYSMEM_BITS is wrong. You should use
MAX_PHYSMEM_BITS.
E.g. on x86_64, MAX_POSSIBLE_PHYSMEM_BITS is 52, while MAX_PHYSMEM_BITS
is (pgtable_l5_enabled() ? 52 : 46) - so MAX_PHYSMEM_BITS depends on the
actual HW.
> +int check_hotplug_memory_addressable(u64 start, u64 size)
> +{
> +#ifdef MAX_POSSIBLE_PHYSMEM_BITS
> + if ((start + size - 1) >> MAX_POSSIBLE_PHYSMEM_BITS)
> + return -E2BIG;
> +#endif
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(check_hotplug_memory_addressable);
> +
> static int check_hotplug_memory_range(u64 start, u64 size)
> {
> /* memory range must be block size aligned */
> @@ -1040,7 +1057,7 @@ static int check_hotplug_memory_range(u64 start, u64
> size)
> return -EINVAL;
> }
>
> - return 0;
> + return check_hotplug_memory_addressable(start, size);
> }
>
> static int online_memory_block(struct memory_block *mem, void *arg)
>
--
Thanks,
David / dhildenb
Re: [PATCH 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()
On 10.09.19 04:52, Alastair D'Silva wrote:
> From: Alastair D'Silva
>
> On PowerPC, the address ranges allocated to OpenCAPI LPC memory
> are allocated from firmware. These address ranges may be higher
> than what older kernels permit, as we increased the maximum
> permissable address in commit 4ffe713b7587
> ("powerpc/mm: Increase the max addressable memory to 2PB"). It is
> possible that the addressable range may change again in the
> future.
>
> In this scenario, we end up with a bogus section returned from
> __section_nr (see the discussion on the thread "mm: Trigger bug on
> if a section is not found in __section_nr").
>
> Adding a check here means that we fail early and have an
> opportunity to handle the error gracefully, rather than rumbling
> on and potentially accessing an incorrect section.
>
> Further discussion is also on the thread ("powerpc: Perform a bounds
> check in arch_add_memory").
>
> Signed-off-by: Alastair D'Silva
> ---
> include/linux/memory_hotplug.h | 1 +
> mm/memory_hotplug.c| 19 ++-
> 2 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index f46ea71b4ffd..bc477e98a310 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -110,6 +110,7 @@ extern void __online_page_increment_counters(struct page
> *page);
> extern void __online_page_free(struct page *page);
>
> extern int try_online_node(int nid);
> +int check_hotplug_memory_addressable(u64 start, u64 size);
>
> extern int arch_add_memory(int nid, u64 start, u64 size,
> struct mhp_restrictions *restrictions);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index c73f09913165..3c5428b014f9 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1030,6 +1030,23 @@ int try_online_node(int nid)
> return ret;
> }
>
> +#ifndef MAX_POSSIBLE_PHYSMEM_BITS
> +#ifdef MAX_PHYSMEM_BITS
> +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
> +#endif
> +#endif
> +
I think using MAX_POSSIBLE_PHYSMEM_BITS bits is wrong. You should use
MAX_PHYSMEM_BITS.
E.g. on x86_64, MAX_POSSIBLE_PHYSMEM_BITS is 52, while MAX_PHYSMEM_BITS
is (pgtable_l5_enabled() ? 52 : 46) - so MAX_PHYSMEM_BITS depends on the
actual HW.
> +int check_hotplug_memory_addressable(u64 start, u64 size)
> +{
> +#ifdef MAX_POSSIBLE_PHYSMEM_BITS
> + if ((start + size - 1) >> MAX_POSSIBLE_PHYSMEM_BITS)
> + return -E2BIG;
> +#endif
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(check_hotplug_memory_addressable);
> +
> static int check_hotplug_memory_range(u64 start, u64 size)
> {
> /* memory range must be block size aligned */
> @@ -1040,7 +1057,7 @@ static int check_hotplug_memory_range(u64 start, u64
> size)
> return -EINVAL;
> }
>
> - return 0;
> + return check_hotplug_memory_addressable(start, size);
> }
>
> static int online_memory_block(struct memory_block *mem, void *arg)
>
--
Thanks,
David / dhildenb
