Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753793AbcJELpe (ORCPT ); Wed, 5 Oct 2016 07:45:34 -0400 Received: from mail.kernel.org ([198.145.29.136]:50702 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750774AbcJELpc (ORCPT ); Wed, 5 Oct 2016 07:45:32 -0400 Date: Wed, 5 Oct 2016 08:45:24 -0300 From: Arnaldo Carvalho de Melo To: Krister Johansen Cc: Masami Hiramatsu , Namhyung Kim , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , linux-kernel@vger.kernel.org Subject: callchain map refcounting fixes was Re: [PATCH perf/core] perf script: fix a use after free crash. Message-ID: <20161005114524.GY7143@kernel.org> References: <20161002031336.GA2635@templeofstupid.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20161002031336.GA2635@templeofstupid.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5566 Lines: 179 Em Sat, Oct 01, 2016 at 08:13:36PM -0700, Krister Johansen escreveu: > If dso__load_kcore frees all of the existing maps, but one has already > been attached to a callchain cursor node, then we can get a SIGSEGV in > any function that happens to try to use this cursor with the invalid > map. Use the existing map refcount mechanism to forestall cleanup of a > map until the cursor iterates past the node. Seems ok, thanks for working on this! Can you provide a test case that causes the SEGV so that I can, in addition to reviewing your changes and auditing the code to check if all cases ara plugged, to reproduce the problem? Fr?d?ric, Namhyung, Ack? Masami, is this a case that your refcount validator can catch? - Arnaldo > Signed-off-by: Krister Johansen > --- > tools/perf/util/callchain.c | 12 ++++++++++-- > tools/perf/util/callchain.h | 20 ++++++++++++++++++++ > tools/perf/util/hist.c | 4 ++++ > 3 files changed, 34 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c > index 07fd30b..15c89b2 100644 > --- a/tools/perf/util/callchain.c > +++ b/tools/perf/util/callchain.c > @@ -439,7 +439,7 @@ fill_node(struct callchain_node *node, struct callchain_cursor *cursor) > } > call->ip = cursor_node->ip; > call->ms.sym = cursor_node->sym; > - call->ms.map = cursor_node->map; > + call->ms.map = map__get(cursor_node->map); > list_add_tail(&call->list, &node->val); > > callchain_cursor_advance(cursor); > @@ -464,6 +464,7 @@ add_child(struct callchain_node *parent, > > list_for_each_entry_safe(call, tmp, &new->val, list) { > list_del(&call->list); > + map__zput(call->ms.map); > free(call); > } > free(new); > @@ -732,6 +733,7 @@ merge_chain_branch(struct callchain_cursor *cursor, > callchain_cursor_append(cursor, list->ip, > list->ms.map, list->ms.sym); > list_del(&list->list); > + map__zput(list->ms.map); > free(list); > } > > @@ -780,7 +782,8 @@ int callchain_cursor_append(struct callchain_cursor *cursor, > } > > node->ip = ip; > - node->map = map; > + map__zput(node->map); > + node->map = map__get(map); > node->sym = sym; > > cursor->nr++; > @@ -830,6 +833,8 @@ int fill_callchain_info(struct addr_location *al, struct callchain_cursor_node * > goto out; > } > > + map__get(al->map); > + > if (al->map->groups == &al->machine->kmaps) { > if (machine__is_host(al->machine)) { > al->cpumode = PERF_RECORD_MISC_KERNEL; > @@ -947,11 +952,13 @@ static void free_callchain_node(struct callchain_node *node) > > list_for_each_entry_safe(list, tmp, &node->parent_val, list) { > list_del(&list->list); > + map__zput(list->ms.map); > free(list); > } > > list_for_each_entry_safe(list, tmp, &node->val, list) { > list_del(&list->list); > + map__zput(list->ms.map); > free(list); > } > > @@ -1035,6 +1042,7 @@ int callchain_node__make_parent_list(struct callchain_node *node) > out: > list_for_each_entry_safe(chain, new, &head, list) { > list_del(&chain->list); > + map__zput(chain->ms.map); > free(chain); > } > return -ENOMEM; > diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h > index 13e7554..0d944ef 100644 > --- a/tools/perf/util/callchain.h > +++ b/tools/perf/util/callchain.h > @@ -5,6 +5,7 @@ > #include > #include > #include "event.h" > +#include "map.h" > #include "symbol.h" > > #define HELP_PAD "\t\t\t\t" > @@ -178,8 +179,13 @@ int callchain_merge(struct callchain_cursor *cursor, > */ > static inline void callchain_cursor_reset(struct callchain_cursor *cursor) > { > + struct callchain_cursor_node *node; > + > cursor->nr = 0; > cursor->last = &cursor->first; > + > + for (node = cursor->first; node != NULL; node = node->next) > + map__zput(node->map); > } > > int callchain_cursor_append(struct callchain_cursor *cursor, u64 ip, > @@ -238,12 +244,26 @@ int perf_callchain_config(const char *var, const char *value); > static inline void callchain_cursor_snapshot(struct callchain_cursor *dest, > struct callchain_cursor *src) > { > + struct callchain_cursor_node *node; > + > *dest = *src; > > dest->first = src->curr; > dest->nr -= src->pos; > + > + for (node = dest->first; node != NULL; node = node->next) > + map__get(node->map); > } > > +static inline void callchain_cursor_snapshot_rele(struct callchain_cursor *curs) > +{ > + struct callchain_cursor_node *node; > + > + for (node = curs->first; node != NULL; node = node->next) > + map__put(node->map); > +} > + > + > #ifdef HAVE_SKIP_CALLCHAIN_IDX > int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain); > #else > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c > index b02992e..f8335e8 100644 > --- a/tools/perf/util/hist.c > +++ b/tools/perf/util/hist.c > @@ -1,6 +1,7 @@ > #include "util.h" > #include "build-id.h" > #include "hist.h" > +#include "map.h" > #include "session.h" > #include "sort.h" > #include "evlist.h" > @@ -970,6 +971,8 @@ iter_add_next_cumulative_entry(struct hist_entry_iter *iter, > > if (symbol_conf.use_callchain) > callchain_append(he->callchain, &cursor, sample->period); > + /* Cleanup temporary cursor. */ > + callchain_cursor_snapshot_rele(&cursor); > return 0; > } > > @@ -979,6 +982,7 @@ iter_finish_cumulative_entry(struct hist_entry_iter *iter, > { > zfree(&iter->priv); > iter->he = NULL; > + map__zput(al->map); > > return 0; > } > -- > 2.7.4