To correctly handle 32-bit and 64-bit mmap() syscalls in 64bit applications its required to have separate address bases to place a mapping.
The tasksize can be used as an indicator to select the proper parameters for mmap_base(). This requires the following changes: - Add task_size argument to mmap_base() and make the calculation based on it. - Provide mmap_legacy_base() as a seperate function - Use the new functions in arch_pick_mmap_layout() [ tglx: Massaged changelog ] Signed-off-by: Dmitry Safonov <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Andy Lutomirski <[email protected]> Cc: Cyrill Gorcunov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> [ms commit 8f3e474f3cea] Signed-off-by: Dmitry Safonov <[email protected]> --- arch/x86/include/asm/elf.h | 29 ++++++++++----------- arch/x86/include/asm/processor.h | 4 ++- arch/x86/mm/mmap.c | 56 +++++++++++++++++++++------------------- 3 files changed, 45 insertions(+), 44 deletions(-) diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index e114fff00087..e7057133088d 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -277,8 +277,19 @@ do { \ } \ } while (0) +/* + * True on X86_32 or when emulating IA32 on X86_64 + */ +static inline int mmap_is_ia32(void) +{ + return IS_ENABLED(CONFIG_X86_32) || + (IS_ENABLED(CONFIG_COMPAT) && + test_thread_flag(TIF_ADDR32)); +} + #ifdef CONFIG_X86_32 +#define __STACK_RND_MASK(is32bit) (0x7ff) #define STACK_RND_MASK (0x7ff) #define VDSO_HIGH_BASE (__fix_to_virt(FIX_VDSO)) @@ -292,7 +303,8 @@ do { \ #define VDSO_HIGH_BASE 0xffffe000U /* CONFIG_COMPAT_VDSO address */ /* 1GB for 64bit, 8MB for 32bit */ -#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff) +#define __STACK_RND_MASK(is32bit) ((is32bit) ? 0x7ff : 0x3fffff) +#define STACK_RND_MASK __STACK_RND_MASK(mmap_is_ia32()) #define ARCH_DLINFO \ do { \ @@ -343,21 +355,6 @@ extern int do_map_compat_vdso(unsigned long addr); extern unsigned long arch_randomize_brk(struct mm_struct *mm); #define arch_randomize_brk arch_randomize_brk -/* - * True on X86_32 or when emulating IA32 on X86_64 - */ -static inline int mmap_is_ia32(void) -{ -#ifdef CONFIG_X86_32 - return 1; -#endif -#ifdef CONFIG_IA32_EMULATION - if (test_thread_flag(TIF_ADDR32)) - return 1; -#endif - return 0; -} - /* Do not change the values. See get_align_mask() */ enum align_flags { ALIGN_VA_32 = BIT(0), diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 0c4e3faf8ac3..47a1ac9e1c10 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -841,6 +841,7 @@ static inline void spin_lock_prefetch(const void *x) /* * User space process size: 3GB (default). */ +#define IA32_PAGE_OFFSET PAGE_OFFSET #define TASK_SIZE PAGE_OFFSET #define TASK_SIZE_MAX TASK_SIZE #define STACK_TOP TASK_SIZE @@ -949,7 +950,8 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_ip, * This decides where the kernel will search for a free chunk of vm * space during mmap's. */ -#define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 3)) +#define __TASK_UNMAPPED_BASE(task_size) (PAGE_ALIGN(task_size / 3)) +#define TASK_UNMAPPED_BASE __TASK_UNMAPPED_BASE(TASK_SIZE) #define KSTK_EIP(task) (task_pt_regs(task)->ip) diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 83a986ef7651..d0c222d64bb1 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -35,25 +35,23 @@ struct __read_mostly va_alignment va_align = { .flags = -1, }; -static unsigned long stack_maxrandom_size(void) +static inline unsigned long tasksize_32bit(void) +{ + return IA32_PAGE_OFFSET; +} + +static unsigned long stack_maxrandom_size(unsigned long task_size) { unsigned long max = 0; if ((current->flags & PF_RANDOMIZE) && !(current->personality & ADDR_NO_RANDOMIZE)) { - max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT; + max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit()); + max <<= PAGE_SHIFT; } return max; } -/* - * Top of mmap area (just below the process stack). - * - * Leave an at least ~128 MB hole with possible stack randomization. - */ -#define MIN_GAP (128*1024*1024UL + stack_maxrandom_size()) -#define MAX_GAP (TASK_SIZE/6*5) - #ifdef CONFIG_COMPAT # define mmap32_rnd_bits 8 # define mmap64_rnd_bits 28 @@ -62,6 +60,8 @@ static unsigned long stack_maxrandom_size(void) # define mmap64_rnd_bits 28 #endif +#define SIZE_128M (128 * 1024 * 1024UL) + static int mmap_is_legacy(void) { if (current->personality & ADDR_COMPAT_LAYOUT) @@ -84,28 +84,30 @@ unsigned long arch_mmap_rnd(void) return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits); } -static unsigned long mmap_base(unsigned long rnd) +static unsigned long mmap_base(unsigned long rnd, unsigned long task_size) { unsigned long gap = rlimit(RLIMIT_STACK); + unsigned long gap_min, gap_max; + + /* + * Top of mmap area (just below the process stack). + * Leave an at least ~128 MB hole with possible stack randomization. + */ + gap_min = SIZE_128M + stack_maxrandom_size(task_size); + gap_max = (task_size / 6) * 5; - if (gap < MIN_GAP) - gap = MIN_GAP; - else if (gap > MAX_GAP) - gap = MAX_GAP; + if (gap < gap_min) + gap = gap_min; + else if (gap > gap_max) + gap = gap_max; - return PAGE_ALIGN(TASK_SIZE - gap - rnd); + return PAGE_ALIGN(task_size - gap - rnd); } -/* - * Bottom-up (legacy) layout on X86_32 did not support randomization, X86_64 - * does, but not when emulating X86_32 - */ -static unsigned long mmap_legacy_base(unsigned long rnd) +static unsigned long mmap_legacy_base(unsigned long rnd, + unsigned long task_size) { - if (mmap_is_ia32()) - return TASK_UNMAPPED_BASE; - else - return TASK_UNMAPPED_BASE + rnd; + return __TASK_UNMAPPED_BASE(task_size) + rnd; } /* @@ -119,14 +121,14 @@ void arch_pick_mmap_layout(struct mm_struct *mm) if (current->flags & PF_RANDOMIZE) random_factor = arch_mmap_rnd(); - mm->mmap_legacy_base = mmap_legacy_base(random_factor); + mm->mmap_legacy_base = mmap_legacy_base(random_factor, TASK_SIZE); if (mmap_is_legacy()) { mm->mmap_base = mm->mmap_legacy_base; mm->get_unmapped_area = arch_get_unmapped_area; mm->unmap_area = arch_unmap_area; } else { - mm->mmap_base = mmap_base(random_factor); + mm->mmap_base = mmap_base(random_factor, TASK_SIZE); mm->get_unmapped_area = arch_get_unmapped_area_topdown; mm->unmap_area = arch_unmap_area_topdown; } -- 2.12.2 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
