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    SubjectRe: [PATCH] [RESEND] i386 and x86_64: randomize brk()
    On Tue, 11 Sep 2007 14:17:24 +0200 (CEST) Jiri Kosina <jkosina@suse.cz> wrote:

    > From: Jiri Kosina <jkosina@suse.cz>
    >
    > i386 and x86_64: randomize brk()
    >
    > This patch randomizes the location of the heap (brk) for i386 and x86_64.
    > The range is randomized in the range starting at current brk location up
    > to 0x02000000 offset for both architectures. This, together with
    > pie-executable-randomization.patch and
    > pie-executable-randomization-fix.patch, should make the address space
    > randomization on i386 and x86_64 complete.
    >
    > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
    >
    > diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
    > index 8466471..8e0624d 100644
    > --- a/arch/i386/kernel/process.c
    > +++ b/arch/i386/kernel/process.c
    > @@ -949,3 +949,17 @@ unsigned long arch_align_stack(unsigned long sp)
    > sp -= get_random_int() % 8192;
    > return sp & ~0xf;
    > }
    > +
    > +unsigned long arch_randomize_brk(unsigned long brk)
    > +{
    > + unsigned long new_brk;
    > + unsigned long range_end;
    > +
    > + range_end = brk + 0x02000000;
    > + new_brk = randomize_range(brk, range_end, 0);
    > + if (new_brk)
    > + return new_brk;
    > + else
    > + return brk;
    > +}
    > +
    > diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
    > index 2842f50..b20f0eb 100644
    > --- a/arch/x86_64/kernel/process.c
    > +++ b/arch/x86_64/kernel/process.c
    > @@ -902,3 +902,17 @@ unsigned long arch_align_stack(unsigned long sp)
    > sp -= get_random_int() % 8192;
    > return sp & ~0xf;
    > }
    > +
    > +unsigned long arch_randomize_brk(unsigned long brk)
    > +{
    > + unsigned long new_brk;
    > + unsigned long range_end;
    > +
    > + range_end = brk + 0x02000000;
    > + new_brk = randomize_range(brk, range_end, 0);
    > + if (new_brk)
    > + return new_brk;
    > + else
    > + return brk;
    > +}
    > +
    > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
    > index d65f1d9..7afec71 100644
    > --- a/fs/binfmt_elf.c
    > +++ b/fs/binfmt_elf.c
    > @@ -47,6 +47,9 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs);
    > static int load_elf_library(struct file *);
    > static unsigned long elf_map (struct file *, unsigned long, struct elf_phdr *, int, int, unsigned long);
    >
    > +/* overriden by architectures supporting brk randomization */
    > +unsigned long __weak arch_randomize_brk(unsigned long brk) { return brk; }
    > +
    > /*
    > * If we don't support core dumping, then supply a NULL so we
    > * don't even try.
    > @@ -1073,6 +1076,10 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
    > current->mm->end_data = end_data;
    > current->mm->start_stack = bprm->p;
    >
    > + if (current->flags & PF_RANDOMIZE)
    > + current->mm->brk = current->mm->start_brk =
    > + arch_randomize_brk(current->mm->brk);
    > +
    > if (current->personality & MMAP_PAGE_ZERO) {
    > /* Why this, you ask??? Well SVr4 maps page 0 as read-only,
    > and some applications "depend" upon this behavior.

    We need a prototype of arch_randomize_brk() in scope for all callers and
    implementations, so that the compiler can perform the appropriate
    typechecking.

    --- a/include/linux/mm.h~i386-and-x86_64-randomize-brk-fix
    +++ a/include/linux/mm.h
    @@ -1017,6 +1017,7 @@ out:
    extern int do_munmap(struct mm_struct *, unsigned long, size_t);

    extern unsigned long do_brk(unsigned long, unsigned long);
    +extern unsigned long arch_randomize_brk(unsigned long brk);

    /* filemap.c */
    extern unsigned long page_unuse(struct page *);
    _
    -
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