On Tue, May 18, 2021 at 11:28:55AM +0300, Dan Carpenter wrote: > On Mon, May 17, 2021 at 06:57:33PM +0300, Dan Carpenter wrote: > > Thanks for catching these... I've created a new Smatch static checker > > warning for this but it only works for list_for_each_entry(). > > Eventually someone would have run the coccinelle script to convert these > > list_for_each loops into list_for_each_entry(). Otherwise you have to > > parse container_of() and I've been meaning to do that for a while but I > > haven't yet. > > > > Anyway, I'm going to test it out overnight and see what it finds. It's > > sort a new use for the modification_hook(), before I had only ever used > > it to silence warnings but this check uses it to trigger warnings. So > > perhaps it will generate a lot of false positives. We'll see. > > > > It sets the state of the iterator to &start at the start of the loop > > and if it's not &start state at the end then it prints a warning. > > > > regards, > > dan carpenter > > > > That Smatch check didn't work at all. :P Back to the drawing board. > > regards, > dan carpenter It's sort of working now. I just had to get some ordering issues fixed. Also I had to fix a bug in smatch_conditions.c... The check itself works very well, but the heuristic is a bit off. It turns out we some times mess with the list iterator very intentionally. For example, one thing people do is add a new item directly after the current item. About 8 out of the 32 warnings listed below are real issues. I'm going to send some patches and bug fixes for them. A couple are too ancient for and complicated to bother with. regards, dan carpenter kernel/exit.c:1397 do_wait_thread() warn: iterator 'p->sibling.next' changed during iteration kernel/exit.c:1411 ptrace_do_wait() warn: iterator 'p->ptrace_entry.next' changed during iteration kernel/events/core.c:3220 perf_event_modify_attr() warn: iterator 'child->child_list.next' changed during iteration kernel/events/core.c:5451 perf_event_for_each_child() warn: iterator 'child->child_list.next' changed during iteration kernel/locking/locktorture.c:420 torture_ww_mutex_lock() warn: iterator 'll->link.next' changed during iteration kernel/locking/test-ww_mutex.c:464 stress_reorder_work() warn: iterator 'll->link.next' changed during iteration arch/x86/kvm/../../../virt/kvm/kvm_main.c:4866 vm_stat_clear() warn: iterator 'kvm->vm_list.next' changed during iteration fs/btrfs/extent-tree.c:4230 find_free_extent() warn: iterator 'block_group->list.next' changed during iteration fs/nilfs2/segment.c:1565 nilfs_segctor_update_payload_blocknr() warn: iterator 'bh->b_assoc_buffers.next' changed during iteration fs/super.c:657 __iterate_supers() warn: iterator 'sb->s_list.next' changed during iteration drivers/spi/spi-fsi.c:469 fsi_spi_transfer_one_message() warn: iterator 'transfer->transfer_list.next' changed during iteration drivers/spi/spi-tegra210-quad.c:990 tegra_qspi_transfer_one_message() warn: iterator 'transfer->transfer_list.next' changed during iteration drivers/spi/spi.c:3299 spi_split_transfers_maxsize() warn: iterator 'xfer->transfer_list.next' changed during iteration drivers/staging/emxx_udc/emxx_udc.c:2079 _nbu2ss_nuke() warn: iterator 'req->queue.next' changed during iteration drivers/pnp/quirks.c:59 quirk_awe32_resources() warn: iterator 'option->list.next' changed during iteration drivers/usb/dwc3/gadget.c:1298 dwc3_prepare_trbs() warn: iterator 'req->list.next' changed during iteration drivers/gpu/drm/ttm/ttm_device.c:145 ttm_device_swapout() warn: iterator 'bo->lru.next' changed during iteration drivers/gpu/drm/ttm/ttm_execbuf_util.c:91 ttm_eu_reserve_buffers() warn: iterator 'entry->head.next' changed during iteration drivers/gpu/drm/i915/gt/intel_reset.c:901 __intel_gt_unset_wedged() warn: iterator 'tl->link.next' changed during iteration drivers/target/target_core_user.c:1264 tcmu_tmr_notify() warn: iterator 'se_cmd->state_list.next' changed during iteration drivers/w1/w1.c:1265 w1_fini() warn: iterator 'dev->w1_master_entry.next' changed during iteration drivers/scsi/libsas/sas_port.c:47 sas_resume_port() warn: iterator 'dev->dev_list_node.next' changed during iteration drivers/scsi/lpfc/lpfc_hbadisc.c:993 lpfc_linkup_cleanup_nodes() warn: iterator 'ndlp->nlp_listp.next' changed during iteration drivers/scsi/lpfc/lpfc_hbadisc.c:4983 lpfc_unreg_hba_rpis() warn: iterator 'ndlp->nlp_listp.next' changed during iteration drivers/block/drbd/drbd_debugfs.c:311 seq_print_resource_transfer_log_summary() warn: iterator 'req->tl_requests.next' changed during iteration drivers/infiniband/hw/mlx5/main.c:3285 mlx5_ib_init_multiport_master() warn: iterator 'mpi->list.next' changed during iteration drivers/infiniband/core/verbs.c:1112 __ib_shared_qp_event_handler() warn: iterator 'event->element.qp->open_list.next' changed during iteration net/core/devlink.c:10589 devlink_pernet_pre_exit() warn: iterator 'devlink->list.next' changed during iteration net/bluetooth/l2cap_core.c:1726 l2cap_conn_ready() warn: iterator 'chan->list.next' changed during iteration net/bluetooth/l2cap_core.c:6265 l2cap_ecred_reconf_rsp() warn: iterator 'chan->list.next' changed during iteration net/bluetooth/l2cap_core.c:8209 l2cap_security_cfm() warn: iterator 'chan->list.next' changed during iteration security/landlock/fs.c:347 hook_sb_delete() warn: iterator 'inode->i_sb_list.next' changed during iteration /* * Copyright (C) 2021 Oracle. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt */ #include "smatch.h" #include "smatch_extra.h" static int my_id; STATE(start); STATE(watch); static struct statement *iterator_stmt, *pre_stmt, *post_stmt; static bool stmt_matches(struct expression *expr, struct statement *stmt) { struct expression *tmp; struct statement *parent; if (!stmt) return false; while ((tmp = expr_get_parent_expr(expr))) expr = tmp; parent = expr_get_parent_stmt(expr); return parent == stmt; } static void set_watch(struct sm_state *sm, struct expression *mod_expr) { if (mod_expr && stmt_matches(mod_expr, post_stmt)) return; set_state(my_id, sm->name, sm->sym, &watch); } static bool is_list_macro(const char *macro) { if (strcmp(macro, "list_for_each_entry") == 0) return true; return false; } static void match_iterator_statement(struct statement *stmt) { const char *macro; if (stmt->type != STMT_ITERATOR || !stmt->iterator_pre_statement || !stmt->iterator_post_statement) return; macro = get_macro_name(stmt->pos); if (!macro) return; if (!is_list_macro(macro)) return; iterator_stmt = stmt; pre_stmt = stmt->iterator_pre_statement; post_stmt = stmt->iterator_post_statement; } static char *get_iterator_member(void) { struct expression *expr; if (!iterator_stmt || !iterator_stmt->iterator_pre_condition) return NULL; expr = iterator_stmt->iterator_pre_condition; if (expr->type != EXPR_PREOP || expr->op != '!') return NULL; expr = strip_parens(expr->unop); if (expr->type != EXPR_COMPARE) return NULL; expr = strip_parens(expr->left); if (expr->type != EXPR_PREOP || expr->op != '&') return NULL; expr = strip_expr(expr->unop); if (expr->type != EXPR_DEREF || !expr->member) return NULL; return expr->member->name; } static void match_pre_statement(struct expression *expr) { char *name, *member; struct symbol *sym; char buf[64]; if (!stmt_matches(expr, pre_stmt)) return; name = expr_to_var_sym(expr->left, &sym); if (!name) return; member = get_iterator_member(); snprintf(buf, sizeof(buf), "%s->%s.next", name, member); set_state(my_id, buf, sym, &start); } static void match_post_statement(struct expression *expr) { struct smatch_state *state; char *name, *member; struct symbol *sym; char buf[64]; if (!stmt_matches(expr, post_stmt)) return; name = expr_to_var_sym(expr->left, &sym); if (!name) return; member = get_iterator_member(); snprintf(buf, sizeof(buf), "%s->%s.next", name, member); state = get_state(my_id, buf, sym); if (!state || state == &start) return; sm_warning("iterator '%s' changed during iteration", buf); } void check_list_set_inside(int id) { my_id = id; if (option_project != PROJ_KERNEL) return; add_hook(match_iterator_statement, STMT_HOOK); add_hook(match_pre_statement, ASSIGNMENT_HOOK_AFTER); add_hook(match_post_statement, ASSIGNMENT_HOOK); add_modification_hook(my_id, &set_watch); }
