Re: [LTP] [PATCH net v2] net: ip: order the reuseport socket in __inet_hash

[Kuniyuki Iwashima <kuniyu@google.com>]

On Fri, Aug 15, 2025 at 7:18 PM Wei Gao <wegao@suse.com> wrote:
>
> On Mon, Aug 11, 2025 at 01:27:12PM +0800, kernel test robot wrote:
> >
> >
> > Hello,
> >
> > kernel test robot noticed "BUG:KASAN:slab-use-after-free_in__inet_hash" on:
> >
> > commit: 859ca60b71ef223e210d3d003a225d9ca70879fd ("[PATCH net v2] net: ip: order the reuseport socket in __inet_hash")
> > url: https://github.com/intel-lab-lkp/linux/commits/Menglong-Dong/net-ip-order-the-reuseport-socket-in-__inet_hash/20250801-171131
> > base: https://git.kernel.org/cgit/linux/kernel/git/davem/net.git 01051012887329ea78eaca19b1d2eac4c9f601b5
> > patch link: https://lore.kernel.org/all/20250801090949.129941-1-dongml2@chinatelecom.cn/
> > patch subject: [PATCH net v2] net: ip: order the reuseport socket in __inet_hash
> >
> > in testcase: ltp
> > version: ltp-x86_64-6505f9e29-1_20250802
> > with following parameters:
> >
> >       disk: 1HDD
> >       fs: ext4
> >       test: fs_perms_simple
> >
> >
> >
> > config: x86_64-rhel-9.4-ltp
> > compiler: gcc-12
> > test machine: 4 threads 1 sockets Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz (Ivy Bridge) with 8G memory
> >
> > (please refer to attached dmesg/kmsg for entire log/backtrace)
> >
> >
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <oliver.sang@intel.com>
> > | Closes: https://lore.kernel.org/oe-lkp/202508110750.a66a4225-lkp@intel.com
> >
> >
> > kern :err : [  128.186735] BUG: KASAN: slab-use-after-free in __inet_hash (net/ipv4/inet_hashtables.c:749 net/ipv4/inet_hashtables.c:800)
>
> This kasan error not related with LTP case, i guess it triggered by network
> related process such as bind etc. I try to give following patch to fix
> kasan error, correct me if any mistake, thanks.

Note that the report was for the patch in the mailing list
and the patch was not applied to net-next.git nor net.git.


>
> From: Wei Gao <wegao@suse.com>
> Date: Sat, 16 Aug 2025 09:32:56 +0800
> Subject: [PATCH v1] net: Fix BUG:KASAN:slab-use-after-free_in__inet_hash
>
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202508110750.a66a4225-lkp@intel.com
> Signed-off-by: Wei Gao <wegao@suse.com>
> ---
>  include/linux/rculist_nulls.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
> index da500f4ae142..5def9009c507 100644
> --- a/include/linux/rculist_nulls.h
> +++ b/include/linux/rculist_nulls.h
> @@ -57,7 +57,7 @@ static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n)
>   * @node: element of the list.
>   */
>  #define hlist_nulls_pprev_rcu(node) \
> -       (*((struct hlist_nulls_node __rcu __force **)&(node)->pprev))
> +       (*((struct hlist_nulls_node __rcu __force **)(node)->pprev))
>
>  /**
>   * hlist_nulls_del_rcu - deletes entry from hash list without re-initialization
> @@ -175,7 +175,7 @@ static inline void hlist_nulls_add_before_rcu(struct hlist_nulls_node *n,
>  {
>         WRITE_ONCE(n->pprev, next->pprev);
>         n->next = next;
> -       rcu_assign_pointer(hlist_nulls_pprev_rcu(n), n);
> +       rcu_assign_pointer(hlist_nulls_pprev_rcu(next), n);
>         WRITE_ONCE(next->pprev, &n->next);
>  }
>
> --
> 2.43.0
>