[patch 56/73] VM/Security: add security hook to do_brk (CVE-2007-6434)

Greg KH
2008-02-07T00:23:14Z

[-- Attachment #1: vm-security-add-security-hook-to-do_brk.patch --]
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2.6.23-stable review patch. If anyone has any objections, please let us know.
------------------
From: Eric Paris <eparis@redhat.com>

patch ecaf18c15aac8bb9bed7b7aa0e382fe252e275d5 in mainline.

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>
Cc: maximilian attems <max@stro.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
mm/mmap.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1938,6 +1938,10 @@ unsigned long do_brk(unsigned long addr,
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);

--