On Wed, Aug 26, 2020 at 7:32 AM Dan Carpenter <[email protected]> wrote:
>
> There are a few bugs in the error handling for security_load_policy().
>
> 1) If the newpolicy->sidtab allocation fails then it leads to a NULL
> dereference. Also the error code was not set to -ENOMEM on that
> path.
> 2) If policydb_read() failed then we call policydb_destroy() twice
> which meands we call kvfree(p->sym_val_to_name[i]) twice.
> 3) If policydb_load_isids() failed then we call sidtab_destroy() twice
> and that results in a double free in the sidtab_destroy_tree()
> function because entry.ptr_inner and entry.ptr_leaf are not set to
> NULL.
>
> One thing that makes this code nice to deal with is that none of the
> functions return partially allocated data. In other words, the
> policydb_read() either allocates everything successfully or it frees
> all the data it allocates. It never returns a mix of allocated and
> not allocated data.
>
> I re-wrote this to only free the successfully allocated data which
> avoids the double frees. I also re-ordered selinux_policy_free() so
> it's in the reverse order of the allocation function.
>
> Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
> Signed-off-by: Dan Carpenter <[email protected]>
I guess this wasn't against current selinux next branch?
patching file security/selinux/ss/services.c
Hunk #1 succeeded at 2145 (offset 18 lines).
Hunk #2 succeeded at 2263 (offset 39 lines).
Hunk #3 succeeded at 2303 with fuzz 1 (offset 47 lines).
Hunk #4 succeeded at 2323 (offset 42 lines).
But otherwise it looked good to me.
Acked-by: Stephen Smalley <[email protected]>
On Wed, Aug 26, 2020 at 8:49 AM Stephen Smalley
<[email protected]> wrote:
> On Wed, Aug 26, 2020 at 7:32 AM Dan Carpenter <[email protected]> wrote:
> >
> > There are a few bugs in the error handling for security_load_policy().
> >
> > 1) If the newpolicy->sidtab allocation fails then it leads to a NULL
> > dereference. Also the error code was not set to -ENOMEM on that
> > path.
> > 2) If policydb_read() failed then we call policydb_destroy() twice
> > which meands we call kvfree(p->sym_val_to_name[i]) twice.
> > 3) If policydb_load_isids() failed then we call sidtab_destroy() twice
> > and that results in a double free in the sidtab_destroy_tree()
> > function because entry.ptr_inner and entry.ptr_leaf are not set to
> > NULL.
> >
> > One thing that makes this code nice to deal with is that none of the
> > functions return partially allocated data. In other words, the
> > policydb_read() either allocates everything successfully or it frees
> > all the data it allocates. It never returns a mix of allocated and
> > not allocated data.
> >
> > I re-wrote this to only free the successfully allocated data which
> > avoids the double frees. I also re-ordered selinux_policy_free() so
> > it's in the reverse order of the allocation function.
> >
> > Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
> > Signed-off-by: Dan Carpenter <[email protected]>
>
> I guess this wasn't against current selinux next branch?
>
> patching file security/selinux/ss/services.c
> Hunk #1 succeeded at 2145 (offset 18 lines).
> Hunk #2 succeeded at 2263 (offset 39 lines).
> Hunk #3 succeeded at 2303 with fuzz 1 (offset 47 lines).
> Hunk #4 succeeded at 2323 (offset 42 lines).
>
> But otherwise it looked good to me.
>
> Acked-by: Stephen Smalley <[email protected]>
My guess is that Dan was using selinux/next, just not the latest.
Anyway, the patch is now merged into selinux/next but I had to do some
manual fixes so please double check that it looks okay to you. Thanks
everyone.
--
paul moore
http://www.paul-moore.com