Hi mrpre, kernel test robot noticed the following build warnings: https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/mrpre/bpf-Introduce-cpu-affinity-for-sockmap/20241102-001844 base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master patch link: https://lore.kernel.org/r/20241101161624.568527-2-mrpre%40163.com patch subject: [PATCH v2 1/2] bpf: Introduce cpu affinity for sockmap config: i386-randconfig-141-20241102 (https://download.01.org/0day-ci/archive/20241103/202411030036.PSKG1pW3-lkp@xxxxxxxxx/config) compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99) 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 <lkp@xxxxxxxxx> | Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> | Closes: https://lore.kernel.org/r/202411030036.PSKG1pW3-lkp@xxxxxxxxx/ smatch warnings: net/core/sock_map.c:511 sock_map_update_common() warn: variable dereferenced before check 'psock' (see line 492) vim +/psock +511 net/core/sock_map.c 604326b41a6fb9 Daniel Borkmann 2018-10-13 467 static int sock_map_update_common(struct bpf_map *map, u32 idx, ffed654afa8dc1 mrpre 2024-11-02 468 struct sock *sk, u64 flags, s32 target_cpu) 604326b41a6fb9 Daniel Borkmann 2018-10-13 469 { 604326b41a6fb9 Daniel Borkmann 2018-10-13 470 struct bpf_stab *stab = container_of(map, struct bpf_stab, map); 604326b41a6fb9 Daniel Borkmann 2018-10-13 471 struct sk_psock_link *link; 604326b41a6fb9 Daniel Borkmann 2018-10-13 472 struct sk_psock *psock; 604326b41a6fb9 Daniel Borkmann 2018-10-13 473 struct sock *osk; 604326b41a6fb9 Daniel Borkmann 2018-10-13 474 int ret; 604326b41a6fb9 Daniel Borkmann 2018-10-13 475 604326b41a6fb9 Daniel Borkmann 2018-10-13 476 WARN_ON_ONCE(!rcu_read_lock_held()); 604326b41a6fb9 Daniel Borkmann 2018-10-13 477 if (unlikely(flags > BPF_EXIST)) 604326b41a6fb9 Daniel Borkmann 2018-10-13 478 return -EINVAL; 604326b41a6fb9 Daniel Borkmann 2018-10-13 479 if (unlikely(idx >= map->max_entries)) 604326b41a6fb9 Daniel Borkmann 2018-10-13 480 return -E2BIG; 604326b41a6fb9 Daniel Borkmann 2018-10-13 481 604326b41a6fb9 Daniel Borkmann 2018-10-13 482 link = sk_psock_init_link(); 604326b41a6fb9 Daniel Borkmann 2018-10-13 483 if (!link) 604326b41a6fb9 Daniel Borkmann 2018-10-13 484 return -ENOMEM; 604326b41a6fb9 Daniel Borkmann 2018-10-13 485 2004fdbd8a2b56 Cong Wang 2021-03-30 486 ret = sock_map_link(map, sk); 604326b41a6fb9 Daniel Borkmann 2018-10-13 487 if (ret < 0) 604326b41a6fb9 Daniel Borkmann 2018-10-13 488 goto out_free; 604326b41a6fb9 Daniel Borkmann 2018-10-13 489 604326b41a6fb9 Daniel Borkmann 2018-10-13 490 psock = sk_psock(sk); 604326b41a6fb9 Daniel Borkmann 2018-10-13 491 WARN_ON_ONCE(!psock); ffed654afa8dc1 mrpre 2024-11-02 @492 psock->target_cpu = target_cpu; ^^^^^^^^^^^^^^^^^ The patch adds an unchecked dereference 35d2b7ffffc1d9 John Fastabend 2023-08-29 493 spin_lock_bh(&stab->lock); 604326b41a6fb9 Daniel Borkmann 2018-10-13 494 osk = stab->sks[idx]; 604326b41a6fb9 Daniel Borkmann 2018-10-13 495 if (osk && flags == BPF_NOEXIST) { 604326b41a6fb9 Daniel Borkmann 2018-10-13 496 ret = -EEXIST; 604326b41a6fb9 Daniel Borkmann 2018-10-13 497 goto out_unlock; 604326b41a6fb9 Daniel Borkmann 2018-10-13 498 } else if (!osk && flags == BPF_EXIST) { 604326b41a6fb9 Daniel Borkmann 2018-10-13 499 ret = -ENOENT; 604326b41a6fb9 Daniel Borkmann 2018-10-13 500 goto out_unlock; 604326b41a6fb9 Daniel Borkmann 2018-10-13 501 } 604326b41a6fb9 Daniel Borkmann 2018-10-13 502 604326b41a6fb9 Daniel Borkmann 2018-10-13 503 sock_map_add_link(psock, link, map, &stab->sks[idx]); This also dereferences psock btw. 604326b41a6fb9 Daniel Borkmann 2018-10-13 504 stab->sks[idx] = sk; 604326b41a6fb9 Daniel Borkmann 2018-10-13 505 if (osk) 604326b41a6fb9 Daniel Borkmann 2018-10-13 506 sock_map_unref(osk, &stab->sks[idx]); 35d2b7ffffc1d9 John Fastabend 2023-08-29 507 spin_unlock_bh(&stab->lock); 604326b41a6fb9 Daniel Borkmann 2018-10-13 508 return 0; 604326b41a6fb9 Daniel Borkmann 2018-10-13 509 out_unlock: 35d2b7ffffc1d9 John Fastabend 2023-08-29 510 spin_unlock_bh(&stab->lock); 604326b41a6fb9 Daniel Borkmann 2018-10-13 @511 if (psock) ^^^^^ Probably after 6 years of not triggering the WARN_ON_ONCE() on line 490, we can remove this check? 604326b41a6fb9 Daniel Borkmann 2018-10-13 512 sk_psock_put(sk, psock); 604326b41a6fb9 Daniel Borkmann 2018-10-13 513 out_free: 604326b41a6fb9 Daniel Borkmann 2018-10-13 514 sk_psock_free_link(link); 604326b41a6fb9 Daniel Borkmann 2018-10-13 515 return ret; 604326b41a6fb9 Daniel Borkmann 2018-10-13 516 } -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
