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

[Wei Gao <wegao@suse.com>]

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.

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