fs/posix_acl.c: make posix_acl_create() safer and cleaner
If posix_acl_create() returns an error code then "*acl" and "*default_acl"
can be uninitialized or point to freed memory. This is a dangerous thing
to do. For example, it causes a problem in ocfs2_reflink():
fs/ocfs2/refcounttree.c:4327 ocfs2_reflink()
error: potentially using uninitialized 'default_acl'.
I've re-written this so we set the pointers to NULL at the start. I've
added a temporary "clone" variable to hold the value of "*acl" until end.
Setting them to NULL means means we don't need the "no_acl" label. We may
as well remove the "apply_umask" stuff forward and remove that label as
well.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 84bb65b8..4fb17de 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -547,51 +547,45 @@
struct posix_acl **default_acl, struct posix_acl **acl)
{
struct posix_acl *p;
+ struct posix_acl *clone;
int ret;
+ *acl = NULL;
+ *default_acl = NULL;
+
if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
- goto no_acl;
+ return 0;
p = get_acl(dir, ACL_TYPE_DEFAULT);
- if (IS_ERR(p)) {
- if (p == ERR_PTR(-EOPNOTSUPP))
- goto apply_umask;
- return PTR_ERR(p);
+ if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
+ *mode &= ~current_umask();
+ return 0;
}
+ if (IS_ERR(p))
+ return PTR_ERR(p);
- if (!p)
- goto apply_umask;
-
- *acl = posix_acl_clone(p, GFP_NOFS);
- if (!*acl)
+ clone = posix_acl_clone(p, GFP_NOFS);
+ if (!clone)
goto no_mem;
- ret = posix_acl_create_masq(*acl, mode);
+ ret = posix_acl_create_masq(clone, mode);
if (ret < 0)
goto no_mem_clone;
- if (ret == 0) {
- posix_acl_release(*acl);
- *acl = NULL;
- }
+ if (ret == 0)
+ posix_acl_release(clone);
+ else
+ *acl = clone;
- if (!S_ISDIR(*mode)) {
+ if (!S_ISDIR(*mode))
posix_acl_release(p);
- *default_acl = NULL;
- } else {
+ else
*default_acl = p;
- }
- return 0;
-apply_umask:
- *mode &= ~current_umask();
-no_acl:
- *default_acl = NULL;
- *acl = NULL;
return 0;
no_mem_clone:
- posix_acl_release(*acl);
+ posix_acl_release(clone);
no_mem:
posix_acl_release(p);
return -ENOMEM;