On Wed, Apr 3, 2024 at 8:13 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
>
> On Wed, Apr 3, 2024 at 4:38 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> >
> > Hello Ondrej Mosnacek,
> >
> > Commit c3a276111ea2 ("selinux: optimize storage of filename
> > transitions") from Feb 18, 2020 (linux-next), leads to the following
> > Smatch static checker warning:
> >
> > security/selinux/ss/policydb.c:1953 filename_trans_read_helper_compat()
> > warn: missing error code 'rc'
> >
> > security/selinux/ss/policydb.c
> > 1916 static int filename_trans_read_helper_compat(struct policydb *p, void *fp)
> > 1917 {
> > 1918 struct filename_trans_key key, *ft = NULL;
> > 1919 struct filename_trans_datum *last, *datum = NULL;
> > 1920 char *name = NULL;
> > 1921 u32 len, stype, otype;
> > 1922 __le32 buf[4];
> > 1923 int rc;
> > 1924
> > 1925 /* length of the path component string */
> > 1926 rc = next_entry(buf, fp, sizeof(u32));
> > 1927 if (rc)
> > 1928 return rc;
> > 1929 len = le32_to_cpu(buf[0]);
> > 1930
> > 1931 /* path component string */
> > 1932 rc = str_read(&name, GFP_KERNEL, fp, len);
> > 1933 if (rc)
> > 1934 return rc;
> > 1935
> > 1936 rc = next_entry(buf, fp, sizeof(u32) * 4);
> > 1937 if (rc)
> > 1938 goto out;
> > 1939
> > 1940 stype = le32_to_cpu(buf[0]);
> > 1941 key.ttype = le32_to_cpu(buf[1]);
> > 1942 key.tclass = le32_to_cpu(buf[2]);
> > 1943 key.name = name;
> > 1944
> > 1945 otype = le32_to_cpu(buf[3]);
> > 1946
> > 1947 last = NULL;
> > 1948 datum = policydb_filenametr_search(p, &key);
> > 1949 while (datum) {
> > 1950 if (unlikely(ebitmap_get_bit(&datum->stypes, stype - 1))) {
> > 1951 /* conflicting/duplicate rules are ignored */
> > 1952 datum = NULL;
> > --> 1953 goto out;
> >
> > It's not clear just from looking at this, if it should return zero or an
> > error code. The way to silence these warnings in smatch is to add a
> > "rc = 0;" within 5 lines of the goto. Or a comment would also help
> > reviewers.
>
> Thanks Dan,
>
> Based on the comment and rest of the function I believe the right
> choice is to set @rc to zero before the 'goto'. However, let's give
> Ondrej a chance to comment and submit a patch.
Yes, it should be set to zero in that path (and already happens to be
as a result of lines 1936-1937). I will send a patch to set it
explicitly just before the goto to make it clear and less error-prone.
Thank you for the report!
--
Ondrej Mosnacek
Senior Software Engineer, Linux Security - SELinux kernel
Red Hat, Inc.
