2020-01-15 14:55:44

by Michael Bringmann

Subject: [PATCH v2] Fix display of Maximum Memory

Correct overflow problem in calculation+display of Maximum Memory
value to syscfg where 32bits is insufficient.

Signed-off-by: Michael Bringmann <[email protected]>
---
arch/powerpc/platforms/pseries/lparcfg.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index e33e8bc..f00411c 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -433,12 +433,12 @@ static void parse_em_data(struct seq_file *m)

static void maxmem_data(struct seq_file *m)
{
- unsigned long maxmem = 0;
+ u64 maxmem = 0;

- maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
- maxmem += hugetlb_total_pages() * PAGE_SIZE;
+ maxmem += (u64)drmem_info->n_lmbs * drmem_info->lmb_size;
+ maxmem += (u64)hugetlb_total_pages() * PAGE_SIZE;

- seq_printf(m, "MaxMem=%ld\n", maxmem);
+ seq_printf(m, "MaxMem=%llu\n", maxmem);
}

static int pseries_lparcfg_data(struct seq_file *m, void *v)
--
1.8.3.1

2020-01-15 14:58:27

by Christophe Leroy

Subject: Re: [PATCH v2] Fix display of Maximum Memory

Le 15/01/2020 à 15:53, Michael Bringmann a écrit :
> Correct overflow problem in calculation+display of Maximum Memory
> value to syscfg where 32bits is insufficient.
>
> Signed-off-by: Michael Bringmann <[email protected]>

Reviewed-by: Christophe Leroy <[email protected]>

> ---
> arch/powerpc/platforms/pseries/lparcfg.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
> index e33e8bc..f00411c 100644
> --- a/arch/powerpc/platforms/pseries/lparcfg.c
> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
> @@ -433,12 +433,12 @@ static void parse_em_data(struct seq_file *m)
>
> static void maxmem_data(struct seq_file *m)
> {
> - unsigned long maxmem = 0;
> + u64 maxmem = 0;
>
> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
> - maxmem += hugetlb_total_pages() * PAGE_SIZE;
> + maxmem += (u64)drmem_info->n_lmbs * drmem_info->lmb_size;
> + maxmem += (u64)hugetlb_total_pages() * PAGE_SIZE;
>
> - seq_printf(m, "MaxMem=%ld\n", maxmem);
> + seq_printf(m, "MaxMem=%llu\n", maxmem);
> }
>
> static int pseries_lparcfg_data(struct seq_file *m, void *v)
>

2020-01-16 00:45:00

by Tyrel Datwyler

Subject: Re: [PATCH v2] Fix display of Maximum Memory

On 1/15/20 6:53 AM, Michael Bringmann wrote:
> Correct overflow problem in calculation+display of Maximum Memory
> value to syscfg where 32bits is insufficient.
>

Probably needs the following Fixes tag:

Fixes: 772b039fd9a7 ("powerpc/pseries: Export maximum memory value")

otherwise,

Reviewed-by: Tyrel Datwyler <[email protected]>

> Signed-off-by: Michael Bringmann <[email protected]>
> ---
> arch/powerpc/platforms/pseries/lparcfg.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
> index e33e8bc..f00411c 100644
> --- a/arch/powerpc/platforms/pseries/lparcfg.c
> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
> @@ -433,12 +433,12 @@ static void parse_em_data(struct seq_file *m)
>
> static void maxmem_data(struct seq_file *m)
> {
> - unsigned long maxmem = 0;
> + u64 maxmem = 0;
>
> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
> - maxmem += hugetlb_total_pages() * PAGE_SIZE;
> + maxmem += (u64)drmem_info->n_lmbs * drmem_info->lmb_size;
> + maxmem += (u64)hugetlb_total_pages() * PAGE_SIZE;
>
> - seq_printf(m, "MaxMem=%ld\n", maxmem);
> + seq_printf(m, "MaxMem=%llu\n", maxmem);
> }
>
> static int pseries_lparcfg_data(struct seq_file *m, void *v)
>

2020-01-16 06:39:38

by Michael Ellerman

Subject: Re: [PATCH v2] Fix display of Maximum Memory

Michael Bringmann <[email protected]> writes:
> Correct overflow problem in calculation+display of Maximum Memory
> value to syscfg where 32bits is insufficient.
>
> Signed-off-by: Michael Bringmann <[email protected]>
> ---
> arch/powerpc/platforms/pseries/lparcfg.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
> index e33e8bc..f00411c 100644
> --- a/arch/powerpc/platforms/pseries/lparcfg.c
> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
> @@ -433,12 +433,12 @@ static void parse_em_data(struct seq_file *m)
>
> static void maxmem_data(struct seq_file *m)
> {
> - unsigned long maxmem = 0;
> + u64 maxmem = 0;

This is 64-bit only code, so u64 == unsigned long.

> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
> - maxmem += hugetlb_total_pages() * PAGE_SIZE;
> + maxmem += (u64)drmem_info->n_lmbs * drmem_info->lmb_size;

The only problem AFAICS is n_lmbs is int and lmb_size is u32, so this
multiplication will overflow.

> + maxmem += (u64)hugetlb_total_pages() * PAGE_SIZE;

hugetlb_total_pages() already returns unsigned long.

> - seq_printf(m, "MaxMem=%ld\n", maxmem);
> + seq_printf(m, "MaxMem=%llu\n", maxmem);
> }

This should be sufficient?

diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index e33e8bc4b69b..38c306551f76 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -435,10 +435,10 @@ static void maxmem_data(struct seq_file *m)
{
unsigned long maxmem = 0;

- maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
+ maxmem += (unsigned long)drmem_info->n_lmbs * drmem_info->lmb_size;
maxmem += hugetlb_total_pages() * PAGE_SIZE;

- seq_printf(m, "MaxMem=%ld\n", maxmem);
+ seq_printf(m, "MaxMem=%lu\n", maxmem);
}

static int pseries_lparcfg_data(struct seq_file *m, void *v)


cheers

2020-01-17 03:39:57

by Michael Bringmann

Subject: Re: [PATCH v2] Fix display of Maximum Memory

On 1/15/20 11:53 PM, Michael Ellerman wrote:
> Michael Bringmann <[email protected]> writes:
>> Correct overflow problem in calculation+display of Maximum Memory
>> value to syscfg where 32bits is insufficient.
>>
>> Signed-off-by: Michael Bringmann <[email protected]>
>> ---
>> arch/powerpc/platforms/pseries/lparcfg.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
>> index e33e8bc..f00411c 100644
>> --- a/arch/powerpc/platforms/pseries/lparcfg.c
>> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
>> @@ -433,12 +433,12 @@ static void parse_em_data(struct seq_file *m)
>>
>> static void maxmem_data(struct seq_file *m)
>> {
>> - unsigned long maxmem = 0;
>> + u64 maxmem = 0;
>
> This is 64-bit only code, so u64 == unsigned long.
>
>> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
>> - maxmem += hugetlb_total_pages() * PAGE_SIZE;
>> + maxmem += (u64)drmem_info->n_lmbs * drmem_info->lmb_size;
>
> The only problem AFAICS is n_lmbs is int and lmb_size is u32, so this
> multiplication will overflow.
>
>> + maxmem += (u64)hugetlb_total_pages() * PAGE_SIZE;
>
> hugetlb_total_pages() already returns unsigned long.
>
>> - seq_printf(m, "MaxMem=%ld\n", maxmem);
>> + seq_printf(m, "MaxMem=%llu\n", maxmem);
>> }
>
> This should be sufficient?
>
> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
> index e33e8bc4b69b..38c306551f76 100644
> --- a/arch/powerpc/platforms/pseries/lparcfg.c
> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
> @@ -435,10 +435,10 @@ static void maxmem_data(struct seq_file *m)
> {
> unsigned long maxmem = 0;
>
> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
> + maxmem += (unsigned long)drmem_info->n_lmbs * drmem_info->lmb_size;
> maxmem += hugetlb_total_pages() * PAGE_SIZE;
>
> - seq_printf(m, "MaxMem=%ld\n", maxmem);
> + seq_printf(m, "MaxMem=%lu\n", maxmem);
> }
>
> static int pseries_lparcfg_data(struct seq_file *m, void *v)
>
>
> cheers
>

Trying it out.

--
Michael W. Bringmann
Linux Technology Center
IBM Corporation
Tie-Line 363-5196
External: (512) 286-5196
Cell: (512) 466-0650
[email protected]

2020-01-29 05:20:17

by Michael Ellerman

Subject: Re: [PATCH v2] Fix display of Maximum Memory

On Wed, 2020-01-15 at 14:53:59 UTC, Michael Bringmann wrote:
> Correct overflow problem in calculation+display of Maximum Memory
> value to syscfg where 32bits is insufficient.
>
> Signed-off-by: Michael Bringmann <[email protected]>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/f1dbc1c5c70d0d4c60b5d467ba941fba167c12f6

cheers