lkml.org 
[lkml]   [2011]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] perf,top: fix events overflow in top command
Date
The snprintf function returns number of printed characters even
if it cross the size parameter. So passing enough events via '-e'
parameter will cause segmentation fault.

It's reproduced by following command:

perf top -e `perf list | grep Tracepoint | awk -F'[' '\
{gsub(/[[:space:]]+/,"",$1);array[FNR]=$1}END{outputs=array[1];\
for (i=2;i<=FNR;i++){ outputs=outputs "," array[i];};print outputs}'`
Attached patch is adding SNPRINTF macro that provides the
overflow check and returns actuall number of printed characters.

wbr,
jirka


Reported-by: Han Pingtian <phan@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
tools/perf/util/top.c | 30 ++++++++++++++++++------------
1 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/tools/perf/util/top.c b/tools/perf/util/top.c
index 70a9c13..4f869da 100644
--- a/tools/perf/util/top.c
+++ b/tools/perf/util/top.c
@@ -61,6 +61,12 @@ static void rb_insert_active_sym(struct rb_root *tree, struct sym_entry *se)
rb_insert_color(&se->rb_node, tree);
}

+#define SNPRINTF(buf, size, fmt, args...) \
+({ \
+ size_t r = snprintf(buf, size, fmt, ## args); \
+ r > size ? size : r; \
+})
+
size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
{
struct perf_evsel *counter;
@@ -70,7 +76,7 @@ size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
size_t ret = 0;

if (!perf_guest) {
- ret = snprintf(bf, size,
+ ret = SNPRINTF(bf, size,
" PerfTop:%8.0f irqs/sec kernel:%4.1f%%"
" exact: %4.1f%% [", samples_per_sec,
100.0 - (100.0 * ((samples_per_sec - ksamples_per_sec) /
@@ -81,7 +87,7 @@ size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
float guest_kernel_samples_per_sec = top->guest_kernel_samples / top->delay_secs;
float guest_us_samples_per_sec = top->guest_us_samples / top->delay_secs;

- ret = snprintf(bf, size,
+ ret = SNPRINTF(bf, size,
" PerfTop:%8.0f irqs/sec kernel:%4.1f%% us:%4.1f%%"
" guest kernel:%4.1f%% guest us:%4.1f%%"
" exact: %4.1f%% [", samples_per_sec,
@@ -101,38 +107,38 @@ size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
if (top->evlist->nr_entries == 1 || !top->display_weighted) {
struct perf_evsel *first;
first = list_entry(top->evlist->entries.next, struct perf_evsel, node);
- ret += snprintf(bf + ret, size - ret, "%" PRIu64 "%s ",
+ ret += SNPRINTF(bf + ret, size - ret, "%" PRIu64 "%s ",
(uint64_t)first->attr.sample_period,
top->freq ? "Hz" : "");
}

if (!top->display_weighted) {
- ret += snprintf(bf + ret, size - ret, "%s",
+ ret += SNPRINTF(bf + ret, size - ret, "%s",
event_name(top->sym_evsel));
} else list_for_each_entry(counter, &top->evlist->entries, node) {
- ret += snprintf(bf + ret, size - ret, "%s%s",
+ ret += SNPRINTF(bf + ret, size - ret, "%s%s",
counter->idx ? "/" : "", event_name(counter));
}

- ret += snprintf(bf + ret, size - ret, "], ");
+ ret += SNPRINTF(bf + ret, size - ret, "], ");

if (top->target_pid != -1)
- ret += snprintf(bf + ret, size - ret, " (target_pid: %d",
+ ret += SNPRINTF(bf + ret, size - ret, " (target_pid: %d",
top->target_pid);
else if (top->target_tid != -1)
- ret += snprintf(bf + ret, size - ret, " (target_tid: %d",
+ ret += SNPRINTF(bf + ret, size - ret, " (target_tid: %d",
top->target_tid);
else
- ret += snprintf(bf + ret, size - ret, " (all");
+ ret += SNPRINTF(bf + ret, size - ret, " (all");

if (top->cpu_list)
- ret += snprintf(bf + ret, size - ret, ", CPU%s: %s)",
+ ret += SNPRINTF(bf + ret, size - ret, ", CPU%s: %s)",
top->evlist->cpus->nr > 1 ? "s" : "", top->cpu_list);
else {
if (top->target_tid != -1)
- ret += snprintf(bf + ret, size - ret, ")");
+ ret += SNPRINTF(bf + ret, size - ret, ")");
else
- ret += snprintf(bf + ret, size - ret, ", %d CPU%s)",
+ ret += SNPRINTF(bf + ret, size - ret, ", %d CPU%s)",
top->evlist->cpus->nr,
top->evlist->cpus->nr > 1 ? "s" : "");
}
--
1.7.4


\
 
 \ /
  Last update: 2011-03-07 21:53    [from the cache]
©2003-2011 Jasper Spaans