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 <[email protected]> Acked-by: Alan Cox <[email protected]> Cc: Stephen Smalley <[email protected]> Cc: James Morris <[email protected]> Cc: Chris Wright <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
iegor · Dec 5, 2007 · ecaf18c · ecaf18c
1 parent 294a80a
commit ecaf18c
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/mm/mmap.c b/mm/mmap.c
@@ -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);