[PATCH 0/2] perf: fix events overflow in top command

[PATCH 0/2] perf: fix events overflow in top command

[Jiri Olsa]

hi,

there's a way to crash perf top command by specifying multiple
events. Attached is the fix and change to eliminate the events
output in case many events are specified.

attached patches:
1/2 - perf,top: fix events overflow in top command
2/2 - perf,top: dont let events to eat up whole header line

wbr,
jirka
---
 tools/perf/util/top.c |   48 ++++++++++++++++++++++++++++++++++--------------
 1 files changed, 34 insertions(+), 14 deletions(-)

[PATCH 1/2] perf,top: fix events overflow in top command

[Jiri Olsa]

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

[PATCH 2/2] perf,top: dont let events to eat up whole header line

[Jiri Olsa]

Passing multiple events might force out information about pid/tid/cpu.
Attached patch leaves 30 characters for this info at the expense of
the events' names.

wbr,
jirka


Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 tools/perf/util/top.c |   20 +++++++++++++++++---
 1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/top.c b/tools/perf/util/top.c
index 4f869da..75cfe4d 100644
--- a/tools/perf/util/top.c
+++ b/tools/perf/util/top.c
@@ -115,9 +115,23 @@ size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
 	if (!top->display_weighted) {
 		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",
-				counter->idx ? "/" : "", event_name(counter));
+	} else {
+		/*
+		 * Don't let events eat all the space. Leaving 30 bytes
+		 * for the rest should be enough.
+		 */
+		size_t last_pos = size - 30;
+
+		list_for_each_entry(counter, &top->evlist->entries, node) {
+			ret += SNPRINTF(bf + ret, size - ret, "%s%s",
+					counter->idx ? "/" : "",
+					event_name(counter));
+			if (ret > last_pos) {
+				sprintf(bf + last_pos - 3, "..");
+				ret = last_pos - 1;
+				break;
+			}
+		}
 	}
 
 	ret += SNPRINTF(bf + ret, size - ret, "], ");
-- 
1.7.4

Re: [PATCH 1/2] perf,top: fix events overflow in top command

[Arnaldo Carvalho de Melo]

Em Mon, Mar 07, 2011 at 09:13:40PM +0100, Jiri Olsa escreveu:
> 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.

Good catch, applying to perf/urgent.

- Arnaldo

Re: [PATCH 1/2] perf,top: fix events overflow in top command

[Arnaldo Carvalho de Melo]

Em Wed, Mar 09, 2011 at 10:59:25AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Mon, Mar 07, 2011 at 09:13:40PM +0100, Jiri Olsa escreveu:
> > 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.
> 
> Good catch, applying to perf/urgent.

Tried but it doesn't apply nor can I reproduce the overflow (albeit
granted the long line of events is annoying).

So I'm applying both patches to perf/core instead.

- Arnaldo

Re: [PATCH 1/2] perf,top: fix events overflow in top command

[Jiri Olsa]

On Wed, Mar 09, 2011 at 11:06:10AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Mar 09, 2011 at 10:59:25AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Mon, Mar 07, 2011 at 09:13:40PM +0100, Jiri Olsa escreveu:
> > > 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.
> > 
> > Good catch, applying to perf/urgent.
> 
> Tried but it doesn't apply nor can I reproduce the overflow (albeit
> granted the long line of events is annoying).

patches were based on tip tree

hm, it crashes for me on tip tree,
but I haven't checked the perf/core tree..

not sure if it's any help, but while debugging I could see the sigsegv happened
when the pointer was far beyond the 160 chars buffer size,
maybe the buffer got bigger in the perf tree..

jirka

> 
> So I'm applying both patches to perf/core instead.
> 
> - Arnaldo

Re: [PATCH 1/2] perf,top: fix events overflow in top command

[Arnaldo Carvalho de Melo]

Em Wed, Mar 09, 2011 at 03:19:10PM +0100, Jiri Olsa escreveu:
> On Wed, Mar 09, 2011 at 11:06:10AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Mar 09, 2011 at 10:59:25AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Good catch, applying to perf/urgent.
> > 
> > Tried but it doesn't apply nor can I reproduce the overflow (albeit
> > granted the long line of events is annoying).
> 
> patches were based on tip tree
> 
> hm, it crashes for me on tip tree,
> but I haven't checked the perf/core tree..
> 
> not sure if it's any help, but while debugging I could see the sigsegv happened
> when the pointer was far beyond the 160 chars buffer size,
> maybe the buffer got bigger in the perf tree..

Anyway, using tip/master you are using perf/core so the patch was made
against it, I already merged it, will be on my next pull request to
Ingo.

Thanks,

- Arnaldo

[tip:perf/core] perf top: Fix events overflow in top command

[tip-bot for Jiri Olsa]

Commit-ID:  b9a46bba88001504235459c8410f17e6a7e38008
Gitweb:     http://git.kernel.org/tip/b9a46bba88001504235459c8410f17e6a7e38008
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Mon, 7 Mar 2011 21:13:40 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 10 Mar 2011 10:54:13 -0300

perf top: Fix events overflow in top command

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.

Reported-by: Han Pingtian <phan@redhat.com>
Cc: Han Pingtian <phan@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1299528821-17521-2-git-send-email-jolsa@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@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" : "");
 	}

[tip:perf/core] perf top: Don't let events to eat up whole header line

[tip-bot for Jiri Olsa]

Commit-ID:  6547250381eb315acff3d52b4872ad775359407c
Gitweb:     http://git.kernel.org/tip/6547250381eb315acff3d52b4872ad775359407c
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Mon, 7 Mar 2011 21:13:41 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 10 Mar 2011 10:55:00 -0300

perf top: Don't let events to eat up whole header line

Passing multiple events might force out information about pid/tid/cpu.
Attached patch leaves 30 characters for this info at the expense of the
events' names.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Han Pingtian <phan@redhat.com>
LKML-Reference: <1299528821-17521-3-git-send-email-jolsa@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/top.c |   20 +++++++++++++++++---
 1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/top.c b/tools/perf/util/top.c
index 4f869da..75cfe4d 100644
--- a/tools/perf/util/top.c
+++ b/tools/perf/util/top.c
@@ -115,9 +115,23 @@ size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
 	if (!top->display_weighted) {
 		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",
-				counter->idx ? "/" : "", event_name(counter));
+	} else {
+		/*
+		 * Don't let events eat all the space. Leaving 30 bytes
+		 * for the rest should be enough.
+		 */
+		size_t last_pos = size - 30;
+
+		list_for_each_entry(counter, &top->evlist->entries, node) {
+			ret += SNPRINTF(bf + ret, size - ret, "%s%s",
+					counter->idx ? "/" : "",
+					event_name(counter));
+			if (ret > last_pos) {
+				sprintf(bf + last_pos - 3, "..");
+				ret = last_pos - 1;
+				break;
+			}
+		}
 	}
 
 	ret += SNPRINTF(bf + ret, size - ret, "], ");