Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
On Sat, Apr 13, 2019 at 08:41:33PM +0800, Nicolas Boichat wrote:
Dear stable maintainers,
I encountered a similar issue on a 4.19.33 kernel (Chromium OS). On my
board, the system would not even be able to boot if KASLR decides to
map the linear region to the top of the virtual address space. This
happens every 253 boots on average (there are 0xfd possible random
offsets, and only the top one fails).
I tried to debug the issue, and it appears physical memory allocated
for vmemmap and mem_section array would end up at the same location,
corrupting each other early on boot. I could not figure out exactly
why this is happening, but in any case, this patch fixes my issue (no
failure in 744 reboots with 240 unique offsets, and counting...), and
IMHO the ERR_PTR justification in the commit message is enough to
warrant inclusion in -stable branches.
The patch below was committed to mainline as:
commit c8a43c18a97845e7f94ed7d181c11f41964976a2
arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
and should be included in stable branches after this commit:
Fixes: c031a4213c11a5db ("arm64: kaslr: randomize the linear region")
i.e. anything after kernel 4.5 (git describe says v4.5-rc4-62-gc031a4213c11a5d).
I've queued it for 4.9-4.19, thanks for the report.
--
Thanks,
Sasha
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
Dear stable maintainers,
I encountered a similar issue on a 4.19.33 kernel (Chromium OS). On my
board, the system would not even be able to boot if KASLR decides to
map the linear region to the top of the virtual address space. This
happens every 253 boots on average (there are 0xfd possible random
offsets, and only the top one fails).
I tried to debug the issue, and it appears physical memory allocated
for vmemmap and mem_section array would end up at the same location,
corrupting each other early on boot. I could not figure out exactly
why this is happening, but in any case, this patch fixes my issue (no
failure in 744 reboots with 240 unique offsets, and counting...), and
IMHO the ERR_PTR justification in the commit message is enough to
warrant inclusion in -stable branches.
The patch below was committed to mainline as:
commit c8a43c18a97845e7f94ed7d181c11f41964976a2
arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
and should be included in stable branches after this commit:
Fixes: c031a4213c11a5db ("arm64: kaslr: randomize the linear region")
i.e. anything after kernel 4.5 (git describe says v4.5-rc4-62-gc031a4213c11a5d).
Thanks,
Nicolas
On Wed, Jan 16, 2019 at 4:38 PM Yueyi Li wrote:
>
>
>
> On 2019/1/16 15:51, Ard Biesheuvel wrote:
> > On Wed, 16 Jan 2019 at 04:37, Yueyi Li wrote:
> >> OK, thanks. But seems this mail be ignored, do i need re-sent the patch?
> >>
> >> On 2018/12/26 21:49, Ard Biesheuvel wrote:
> >>> On Tue, 25 Dec 2018 at 03:30, Yueyi Li wrote:
> Hi Ard,
>
>
> On 2018/12/24 17:45, Ard Biesheuvel wrote:
> > Does the following change fix your issue as well?
> >
> > index 9b432d9fcada..9dcf0ff75a11 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
> > * memory spans, randomize the linear region as well.
> > */
> >if (memstart_offset_seed > 0 && range >=
> > ARM64_MEMSTART_ALIGN) {
> > - range = range / ARM64_MEMSTART_ALIGN + 1;
> > + range /= ARM64_MEMSTART_ALIGN;
> >memstart_addr -= ARM64_MEMSTART_ALIGN *
> > ((range *
> > memstart_offset_seed) >> 16);
> >}
> Yes, it can fix this also. I just think modify the first *range*
> calculation would be easier to grasp, what do you think?
>
> >>> I don't think there is a difference, to be honest, but I will leave it
> >>> up to the maintainers to decide which approach they prefer.
> > No it has been merged already. It is in v5.0-rc2 I think.
>
> OK, thanks. :-)
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
On 2019/1/16 15:51, Ard Biesheuvel wrote:
> On Wed, 16 Jan 2019 at 04:37, Yueyi Li wrote:
>> OK, thanks. But seems this mail be ignored, do i need re-sent the patch?
>>
>> On 2018/12/26 21:49, Ard Biesheuvel wrote:
>>> On Tue, 25 Dec 2018 at 03:30, Yueyi Li wrote:
Hi Ard,
On 2018/12/24 17:45, Ard Biesheuvel wrote:
> Does the following change fix your issue as well?
>
> index 9b432d9fcada..9dcf0ff75a11 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
> * memory spans, randomize the linear region as well.
> */
>if (memstart_offset_seed > 0 && range >=
> ARM64_MEMSTART_ALIGN) {
> - range = range / ARM64_MEMSTART_ALIGN + 1;
> + range /= ARM64_MEMSTART_ALIGN;
>memstart_addr -= ARM64_MEMSTART_ALIGN *
> ((range *
> memstart_offset_seed) >> 16);
>}
Yes, it can fix this also. I just think modify the first *range*
calculation would be easier to grasp, what do you think?
>>> I don't think there is a difference, to be honest, but I will leave it
>>> up to the maintainers to decide which approach they prefer.
> No it has been merged already. It is in v5.0-rc2 I think.
OK, thanks. :-)
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
On Wed, 16 Jan 2019 at 04:37, Yueyi Li wrote:
>
> OK, thanks. But seems this mail be ignored, do i need re-sent the patch?
>
> On 2018/12/26 21:49, Ard Biesheuvel wrote:
> > On Tue, 25 Dec 2018 at 03:30, Yueyi Li wrote:
> >> Hi Ard,
> >>
> >>
> >> On 2018/12/24 17:45, Ard Biesheuvel wrote:
> >>> Does the following change fix your issue as well?
> >>>
> >>> index 9b432d9fcada..9dcf0ff75a11 100644
> >>> --- a/arch/arm64/mm/init.c
> >>> +++ b/arch/arm64/mm/init.c
> >>> @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
> >>>* memory spans, randomize the linear region as well.
> >>>*/
> >>> if (memstart_offset_seed > 0 && range >=
> >>> ARM64_MEMSTART_ALIGN) {
> >>> - range = range / ARM64_MEMSTART_ALIGN + 1;
> >>> + range /= ARM64_MEMSTART_ALIGN;
> >>> memstart_addr -= ARM64_MEMSTART_ALIGN *
> >>>((range *
> >>> memstart_offset_seed) >> 16);
> >>> }
> >> Yes, it can fix this also. I just think modify the first *range*
> >> calculation would be easier to grasp, what do you think?
> >>
> > I don't think there is a difference, to be honest, but I will leave it
> > up to the maintainers to decide which approach they prefer.
>
No it has been merged already. It is in v5.0-rc2 I think.
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
OK, thanks. But seems this mail be ignored, do i need re-sent the patch?
On 2018/12/26 21:49, Ard Biesheuvel wrote:
> On Tue, 25 Dec 2018 at 03:30, Yueyi Li wrote:
>> Hi Ard,
>>
>>
>> On 2018/12/24 17:45, Ard Biesheuvel wrote:
>>> Does the following change fix your issue as well?
>>>
>>> index 9b432d9fcada..9dcf0ff75a11 100644
>>> --- a/arch/arm64/mm/init.c
>>> +++ b/arch/arm64/mm/init.c
>>> @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
>>>* memory spans, randomize the linear region as well.
>>>*/
>>> if (memstart_offset_seed > 0 && range >=
>>> ARM64_MEMSTART_ALIGN) {
>>> - range = range / ARM64_MEMSTART_ALIGN + 1;
>>> + range /= ARM64_MEMSTART_ALIGN;
>>> memstart_addr -= ARM64_MEMSTART_ALIGN *
>>>((range * memstart_offset_seed)
>>> >> 16);
>>> }
>> Yes, it can fix this also. I just think modify the first *range*
>> calculation would be easier to grasp, what do you think?
>>
> I don't think there is a difference, to be honest, but I will leave it
> up to the maintainers to decide which approach they prefer.
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
On Tue, 25 Dec 2018 at 03:30, Yueyi Li wrote:
>
> Hi Ard,
>
>
> On 2018/12/24 17:45, Ard Biesheuvel wrote:
> > Does the following change fix your issue as well?
> >
> > index 9b432d9fcada..9dcf0ff75a11 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
> > * memory spans, randomize the linear region as well.
> > */
> > if (memstart_offset_seed > 0 && range >=
> > ARM64_MEMSTART_ALIGN) {
> > - range = range / ARM64_MEMSTART_ALIGN + 1;
> > + range /= ARM64_MEMSTART_ALIGN;
> > memstart_addr -= ARM64_MEMSTART_ALIGN *
> > ((range * memstart_offset_seed)
> > >> 16);
> > }
>
> Yes, it can fix this also. I just think modify the first *range*
> calculation would be easier to grasp, what do you think?
>
I don't think there is a difference, to be honest, but I will leave it
up to the maintainers to decide which approach they prefer.
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
Hi Ard,
On 2018/12/24 17:45, Ard Biesheuvel wrote:
> Does the following change fix your issue as well?
>
> index 9b432d9fcada..9dcf0ff75a11 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
> * memory spans, randomize the linear region as well.
> */
> if (memstart_offset_seed > 0 && range >=
> ARM64_MEMSTART_ALIGN) {
> - range = range / ARM64_MEMSTART_ALIGN + 1;
> + range /= ARM64_MEMSTART_ALIGN;
> memstart_addr -= ARM64_MEMSTART_ALIGN *
> ((range * memstart_offset_seed) >>
> 16);
> }
Yes, it can fix this also. I just think modify the first *range*
calculation would be easier to
grasp, what do you think?
Thanks,
Yueyi
Re: [PATCH] arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
On Mon, 24 Dec 2018 at 08:40, Yueyi Li wrote:
>
> When KASLR enaled(CONFIG_RANDOMIZE_BASE=y), the top 4K virtual
> address have chance to be mapped to physical address, but which
> is expected to leave room for ERR_PTR.
>
> Also, it might cause some other warparound issue when somewhere
> use the last memory page but no overflow check. Such as the last
> page compressed by LZO:
>
> [ 2738.034508] Unable to handle kernel NULL pointer dereference at virtual
> address 0009
> [ 2738.034515] Mem abort info:
> [ 2738.034518] Exception class = DABT (current EL), IL = 32 bits
> [ 2738.034520] SET = 0, FnV = 0
> [ 2738.034523] EA = 0, S1PTW = 0
> [ 2738.034524] FSC = 5
> [ 2738.034526] Data abort info:
> [ 2738.034528] ISV = 0, ISS = 0x0005
> [ 2738.034530] CM = 0, WnR = 0
> [ 2738.034533] user pgtable: 4k pages, 39-bit VAs, pgd = 94cee000
> [ 2738.034535] [0009] *pgd=, *pud=
> ...
> [ 2738.034592] pc : lzo1x_1_do_compress+0x198/0x610
> [ 2738.034595] lr : lzo1x_1_compress+0x98/0x3d8
> [ 2738.034597] sp : ff801caa3470 pstate : 00c00145
> [ 2738.034598] x29: ff801caa3500 x28: 1000
> [ 2738.034601] x27: 1000 x26: f000
> [ 2738.034604] x25: 4ebc x24:
> [ 2738.034607] x23: 004c x22: f7b8
> [ 2738.034610] x21: 2e2ee0b3 x20: 2e2ee0bb
> [ 2738.034612] x19: 0fcc x18: f84a
> [ 2738.034615] x17: 801b03d6 x16: 0782
> [ 2738.034618] x15: 2e2ee0bf x14: fff0
> [ 2738.034620] x13: 000f x12: 0020
> [ 2738.034623] x11: 1824429d x10: ffec
> [ 2738.034626] x9 : 0009 x8 :
> [ 2738.034628] x7 : 0868 x6 : 0434
> [ 2738.034631] x5 : 4ebc x4 :
> [ 2738.034633] x3 : ff801caa3510 x2 : 2e2ee000
> [ 2738.034636] x1 : x0 : f000
> ...
> [ 2738.034717] Process kworker/u16:1 (pid: 8705, stack limit =
> 0xff801caa)
> [ 2738.034720] Call trace:
> [ 2738.034722] lzo1x_1_do_compress+0x198/0x610
> [ 2738.034725] lzo_compress+0x48/0x88
> [ 2738.034729] crypto_compress+0x14/0x20
> [ 2738.034733] zcomp_compress+0x2c/0x38
> [ 2738.034736] zram_bvec_rw+0x3d0/0x860
> [ 2738.034738] zram_rw_page+0x88/0xe0
> [ 2738.034742] bdev_write_page+0x70/0xc0
> [ 2738.034745] __swap_writepage+0x58/0x3f8
> [ 2738.034747] swap_writepage+0x40/0x50
> [ 2738.034750] shrink_page_list+0x4fc/0xe58
> [ 2738.034753] reclaim_pages_from_list+0xa0/0x150
> [ 2738.034756] reclaim_pte_range+0x18c/0x1f8
> [ 2738.034759] __walk_page_range+0xf8/0x1e0
> [ 2738.034762] walk_page_range+0xf8/0x130
> [ 2738.034765] reclaim_task_anon+0xcc/0x168
> [ 2738.034767] swap_fn+0x438/0x668
> [ 2738.034771] process_one_work+0x1fc/0x460
> [ 2738.034773] worker_thread+0x2d0/0x478
> [ 2738.034775] kthread+0x110/0x120
> [ 2738.034778] ret_from_fork+0x10/0x18
> [ 2738.034781] Code: 3800167f 54a8 d100066f 1431 (b9400131)
> [ 2738.034784] ---[ end trace 9b5cca106f0e54d1 ]---
> [ 2738.035473] Kernel panic - not syncing: Fatal exception
>
> in = 0xf000
> in_len = 4096
> ip = x9 = 0x0009 overflowed.
>
> Always leave room the last size of ARM64_MEMSTART_ALIGN region
> in linear region.
>
> Signed-off-by: liyueyi
> ---
> arch/arm64/mm/init.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 0340e45..20fe11e 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -439,7 +439,8 @@ void __init arm64_memblock_init(void)
> if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> extern u16 memstart_offset_seed;
> u64 range = linear_region_size -
> - (memblock_end_of_DRAM() -
> memblock_start_of_DRAM());
> + (memblock_end_of_DRAM() -
> memblock_start_of_DRAM()) -
> + ARM64_MEMSTART_ALIGN;
>
> /*
> * If the size of the linear region exceeds, by a sufficient
Does the following change fix your issue as well?
index 9b432d9fcada..9dcf0ff75a11 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -447,7 +447,7 @@ void __init arm64_memblock_init(void)
* memory spans, randomize the linear region as well.
*/
if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
- range = range / ARM64_MEMSTART_ALIGN + 1;
+ range /= ARM64_MEMSTART_ALIGN;
memstart_addr -= ARM64_MEMSTART_ALIGN *
((range * memstart_offset_seed) >> 16);
}
