Commit ecaf18c1 authored Dec 04, 2007 by Eric Paris Committed by Linus Torvalds Dec 05, 2007

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>

parent 294a80a8

mm/mmap.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1934,6 +1934,10 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
		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);