diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2011-01-12 09:55:22 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> | 2011-01-12 09:55:24 +0100 |
| commit | 9046e401e752dba784805a7818f99cc45a39cbff (patch) | |
| tree | 0f05676ac01a7892b7fddf4e9f3a7e335c1f78d1 /arch | |
| parent | 7a63fa1a85d75756368d9c86fff5c1b193de991c (diff) | |
[S390] mmap: consider stack address randomization
Consider stack address randomization when calulating mmap_base for
flexible mmap layout . Because of address randomization the stack
address can be up to 8MB lower than STACK_TOP.
When calculating mmap_base this isn't taken into account, which could
lead to the case that the gap between the real stack top and mmap_base
is lower than what ulimit specifies for the maximum stack size.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/include/asm/elf.h | 2 | ||||
| -rw-r--r-- | arch/s390/mm/mmap.c | 11 |
2 files changed, 12 insertions, 1 deletions
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h index 354d42616c7e..9dbd3e7a3bc3 100644 --- a/arch/s390/include/asm/elf.h +++ b/arch/s390/include/asm/elf.h @@ -206,6 +206,8 @@ do { \ current->mm->context.noexec == 0; \ }) +#define STACK_RND_MASK 0x7ffUL + #define ARCH_DLINFO \ do { \ if (vdso_enabled) \ diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c index 869efbaed3ea..5578740ab9c9 100644 --- a/arch/s390/mm/mmap.c +++ b/arch/s390/mm/mmap.c @@ -30,6 +30,15 @@ #include <asm/pgalloc.h> #include <asm/compat.h> +static unsigned long stack_maxrandom_size(void) +{ + if (!(current->flags & PF_RANDOMIZE)) + return 0; + if (current->personality & ADDR_NO_RANDOMIZE) + return 0; + return STACK_RND_MASK << PAGE_SHIFT; +} + /* * Top of mmap area (just below the process stack). * @@ -47,7 +56,7 @@ static inline unsigned long mmap_base(void) else if (gap > MAX_GAP) gap = MAX_GAP; - return STACK_TOP - (gap & PAGE_MASK); + return STACK_TOP - stack_maxrandom_size() - (gap & PAGE_MASK); } static inline int mmap_is_legacy(void) |