From: Alastair D'Silva <[email protected]>
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")
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Alastair D'Silva <[email protected]>
---
mm/memory_hotplug.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c73f09913165..a5eddf3c3c1f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -278,6 +278,22 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
return 0;
}
+static int check_hotplug_memory_addressable(unsigned long pfn,
+ unsigned long nr_pages)
+{
+ const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
+
+ if (max_addr >> MAX_PHYSMEM_BITS) {
+ const u64 max_allowed = (1ull << (MAX_PHYSMEM_BITS + 1)) - 1;
+ WARN(1,
+ "Hotplugged memory exceeds maximum addressable address, range=%#llx-%#llx, maximum=%#llx\n",
+ PFN_PHYS(pfn), max_addr, max_allowed);
+ return -E2BIG;
+ }
+
+ return 0;
+}
+
/*
* Reasonably generic function for adding memory. It is
* expected that archs that support memory hotplug will
@@ -291,6 +307,10 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
unsigned long nr, start_sec, end_sec;
struct vmem_altmap *altmap = restrictions->altmap;
+ err = check_hotplug_memory_addressable(pfn, nr_pages);
+ if (err)
+ return err;
+
if (altmap) {
/*
* Validate altmap is within bounds of the total request
--
2.21.0
Hi Alastair,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[cannot apply to v5.3 next-20190926]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Alastair-D-Silva/Add-bounds-check-for-Hotplugged-memory/20190930-143107
config: i386-randconfig-g004-201939 (attached as .config)
compiler: gcc-7 (Debian 7.4.0-13) 7.4.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All warnings (new ones prefixed by >>):
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/mm.h:9,
from mm/memory_hotplug.c:9:
mm/memory_hotplug.c: In function 'check_hotplug_memory_addressable':
>> mm/memory_hotplug.c:289:8: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 2 has type 'unsigned int' [-Wformat=]
"Hotplugged memory exceeds maximum addressable address, range=%#llx-%#llx, maximum=%#llx\n",
^
include/asm-generic/bug.h:92:17: note: in definition of macro '__WARN_printf'
__warn_printk(arg); \
^~~
mm/memory_hotplug.c:288:3: note: in expansion of macro 'WARN'
WARN(1,
^~~~
vim +289 mm/memory_hotplug.c
280
281 static int check_hotplug_memory_addressable(unsigned long pfn,
282 unsigned long nr_pages)
283 {
284 const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
285
286 if (max_addr >> MAX_PHYSMEM_BITS) {
287 const u64 max_allowed = (1ull << (MAX_PHYSMEM_BITS + 1)) - 1;
288 WARN(1,
> 289 "Hotplugged memory exceeds maximum addressable address, range=%#llx-%#llx, maximum=%#llx\n",
290 PFN_PHYS(pfn), max_addr, max_allowed);
291 return -E2BIG;
292 }
293
294 return 0;
295 }
296
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On 30.09.19 08:23, Alastair D'Silva wrote:
> From: Alastair D'Silva <[email protected]>
>
> 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")
> http://lkml.kernel.org/r/[email protected]
>
> Signed-off-by: Alastair D'Silva <[email protected]>
> ---
> mm/memory_hotplug.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index c73f09913165..a5eddf3c3c1f 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -278,6 +278,22 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
> return 0;
> }
>
> +static int check_hotplug_memory_addressable(unsigned long pfn,
> + unsigned long nr_pages)
> +{
> + const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
> +
> + if (max_addr >> MAX_PHYSMEM_BITS) {
> + const u64 max_allowed = (1ull << (MAX_PHYSMEM_BITS + 1)) - 1;
I'd move that up, next to max_addr.
Reviewed-by: David Hildenbrand <[email protected]>
--
Thanks,
David / dhildenb