diff mbox series

[v3,09/11] mips: Use STACK_TOP when computing mmap base address

Message ID 20190417052247.17809-10-alex@ghiti.fr (mailing list archive)
State New, archived
Headers show
Series Provide generic top-down mmap layout functions | expand

Commit Message

Alexandre Ghiti April 17, 2019, 5:22 a.m. UTC
mmap base address must be computed wrt stack top address, using TASK_SIZE
is wrong since STACK_TOP and TASK_SIZE are not equivalent.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/mips/mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Kees Cook April 18, 2019, 5:31 a.m. UTC | #1
On Wed, Apr 17, 2019 at 12:32 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>
> mmap base address must be computed wrt stack top address, using TASK_SIZE
> is wrong since STACK_TOP and TASK_SIZE are not equivalent.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  arch/mips/mm/mmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
> index 3ff82c6f7e24..ffbe69f3a7d9 100644
> --- a/arch/mips/mm/mmap.c
> +++ b/arch/mips/mm/mmap.c
> @@ -22,7 +22,7 @@ EXPORT_SYMBOL(shm_align_mask);
>
>  /* gap between mmap and stack */
>  #define MIN_GAP                (128*1024*1024UL)
> -#define MAX_GAP                ((TASK_SIZE)/6*5)
> +#define MAX_GAP                ((STACK_TOP)/6*5)
>  #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
>
>  static int mmap_is_legacy(struct rlimit *rlim_stack)
> @@ -54,7 +54,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
>         else if (gap > MAX_GAP)
>                 gap = MAX_GAP;
>
> -       return PAGE_ALIGN(TASK_SIZE - gap - rnd);
> +       return PAGE_ALIGN(STACK_TOP - gap - rnd);
>  }
>
>  #define COLOUR_ALIGN(addr, pgoff)                              \
> --
> 2.20.1
>
Alexandre Ghiti April 18, 2019, 6:08 a.m. UTC | #2
On 4/18/19 1:31 AM, Kees Cook wrote:
> On Wed, Apr 17, 2019 at 12:32 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>> mmap base address must be computed wrt stack top address, using TASK_SIZE
>> is wrong since STACK_TOP and TASK_SIZE are not equivalent.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Acked-by: Kees Cook <keescook@chromium.org>


Thanks !


>
> -Kees
>
>> ---
>>   arch/mips/mm/mmap.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
>> index 3ff82c6f7e24..ffbe69f3a7d9 100644
>> --- a/arch/mips/mm/mmap.c
>> +++ b/arch/mips/mm/mmap.c
>> @@ -22,7 +22,7 @@ EXPORT_SYMBOL(shm_align_mask);
>>
>>   /* gap between mmap and stack */
>>   #define MIN_GAP                (128*1024*1024UL)
>> -#define MAX_GAP                ((TASK_SIZE)/6*5)
>> +#define MAX_GAP                ((STACK_TOP)/6*5)
>>   #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
>>
>>   static int mmap_is_legacy(struct rlimit *rlim_stack)
>> @@ -54,7 +54,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
>>          else if (gap > MAX_GAP)
>>                  gap = MAX_GAP;
>>
>> -       return PAGE_ALIGN(TASK_SIZE - gap - rnd);
>> +       return PAGE_ALIGN(STACK_TOP - gap - rnd);
>>   }
>>
>>   #define COLOUR_ALIGN(addr, pgoff)                              \
>> --
>> 2.20.1
>>
>
diff mbox series

Patch

diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index 3ff82c6f7e24..ffbe69f3a7d9 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -22,7 +22,7 @@  EXPORT_SYMBOL(shm_align_mask);
 
 /* gap between mmap and stack */
 #define MIN_GAP		(128*1024*1024UL)
-#define MAX_GAP		((TASK_SIZE)/6*5)
+#define MAX_GAP		((STACK_TOP)/6*5)
 #define STACK_RND_MASK	(0x7ff >> (PAGE_SHIFT - 12))
 
 static int mmap_is_legacy(struct rlimit *rlim_stack)
@@ -54,7 +54,7 @@  static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
 	else if (gap > MAX_GAP)
 		gap = MAX_GAP;
 
-	return PAGE_ALIGN(TASK_SIZE - gap - rnd);
+	return PAGE_ALIGN(STACK_TOP - gap - rnd);
 }
 
 #define COLOUR_ALIGN(addr, pgoff)				\