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| author |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2019-03-04 12:33:28 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2019-03-06 09:34:03 +0100 |
| commit | cd479eccd2e057116d504852814402a1e68ead80 (patch) | |
| tree | 4907bc92b607d86fe8b86a21657d85d7186b3f7d /arch/s390 | |
| parent | Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff) | |
| download | linux-dev-cd479eccd2e057116d504852814402a1e68ead80.tar.xz linux-dev-cd479eccd2e057116d504852814402a1e68ead80.zip | |
s390: limit brk randomization to 32MB
For a 64-bit process the randomization of the program break is quite
large with 1GB. That is as big as the randomization of the anonymous
mapping base, for a test case started with '/lib/ld64.so.1 <exec>'
it can happen that the heap is placed after the stack. To avoid
this limit the program break randomization to 32MB for 64-bit and
keep 8MB for 31-bit.
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/elf.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h index 7d22a474a040..f74639a05f0f 100644 --- a/arch/s390/include/asm/elf.h +++ b/arch/s390/include/asm/elf.h @@ -252,11 +252,14 @@ do { \ /* * Cache aliasing on the latest machines calls for a mapping granularity - * of 512KB. For 64-bit processes use a 512KB alignment and a randomization - * of up to 1GB. For 31-bit processes the virtual address space is limited, - * use no alignment and limit the randomization to 8MB. + * of 512KB for the anonymous mapping base. For 64-bit processes use a + * 512KB alignment and a randomization of up to 1GB. For 31-bit processes + * the virtual address space is limited, use no alignment and limit the + * randomization to 8MB. + * For the additional randomization of the program break use 32MB for + * 64-bit and 8MB for 31-bit. */ -#define BRK_RND_MASK (is_compat_task() ? 0x7ffUL : 0x3ffffUL) +#define BRK_RND_MASK (is_compat_task() ? 0x7ffUL : 0x1fffUL) #define MMAP_RND_MASK (is_compat_task() ? 0x7ffUL : 0x3ff80UL) #define MMAP_ALIGN_MASK (is_compat_task() ? 0 : 0x7fUL) #define STACK_RND_MASK MMAP_RND_MASK |