{2.6.22.y} CVE-2007-6434

["Oliver Pinter" <oliver.pntr@gmail.com>]

mainline: ecaf18c15aac8bb9bed7b7aa0e382fe252e275d5

--->8---
commit ecaf18c15aac8bb9bed7b7aa0e382fe252e275d5
Author: Eric Paris <eparis@redhat.com>
Date:   Tue Dec 4 23:45:31 2007 -0800

    VM/Security: add security hook to do_brk

    Given a specifically crafted binary do_brk() can be used to get low pages
    available in userspace virtual memory and can thus be used to circumvent
    the mmap_min_addr low memory protection.  Add security checks in do_brk().

    Signed-off-by: Eric Paris <eparis@redhat.com>
    Acked-by: Alan Cox <alan@redhat.com>
    Cc: Stephen Smalley <sds@tycho.nsa.gov>
    Cc: James Morris <jmorris@namei.org>
    Cc: Chris Wright <chrisw@sous-sol.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index facc1a7..acfc13f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1934,6 +1934,10 @@ unsigned long do_brk(unsigned long addr, unsigned long le
        if (is_hugepage_only_range(mm, addr, len))
                return -EINVAL;

+       error = security_file_mmap(0, 0, 0, 0, addr, 1);
+       if (error)
+               return error;
+
        flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

        error = arch_mmap_check(addr, len, flags);
---8<---
-- 
Thanks,
Oliver