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Message-ID: <20161002031336.GA2635@templeofstupid.com>
Date: Sat, 1 Oct 2016 20:13:36 -0700
From: Krister Johansen <kjlx@...pleofstupid.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH perf/core] perf script: fix a use after free crash.
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.
Signed-off-by: Krister Johansen <kjlx@...pleofstupid.com>
---
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 <linux/list.h>
#include <linux/rbtree.h>
#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
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