[PATCH] perf hists browser: Fix segfault when showing callchain

[PATCH] perf hists browser: Fix segfault when showing callchain

[Namhyung Kim]

When perf report on TUI shows callchain it checks first node has
siblings to determine whether it needs to print percentage value.  But
it missed a case that first node is NULL.  So sometimes it segfaults
like below:

  $ perf top -g
  perf: Segmentation fault
  -------- backtrace --------
  perf[0x4fcefb]
  /usr/lib/libc.so.6(+0x33b20)[0x7f2a35839b20]
  perf(rb_next+0x8)[0x47d3d8]
  perf[0x4f6058]
  perf[0x4f833b]
  perf[0x4f8610]
  perf[0x4f209e]
  perf(ui_browser__run+0x3a)[0x4f2e6a]
  perf[0x4f94ee]
  perf(perf_evlist__tui_browse_hists+0x94)[0x4fbbf4]
  perf[0x444d10]
  /usr/lib/libpthread.so.0(+0x7314)[0x7f2a37070314]
  /usr/lib/libc.so.6(clone+0x6d)[0x7f2a358ee5bd]

  $ addr2line -e `which perf` 0x4f6058
  /home/namhyung/project/linux/tools/perf/ui/browsers/hists.c:553

I don't know why the backtrace didn't print some symbols..

Fixes: 4087d11cd945 ("perf hists browser: Print overhead percent value for first-level callchain")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/ui/browsers/hists.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index e6bb04b5b09b..788506eef567 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -550,7 +550,7 @@ static int hist_browser__show_callchain(struct hist_browser *browser,
 	bool need_percent;
 
 	node = rb_first(root);
-	need_percent = !!rb_next(node);
+	need_percent = node && rb_next(node);
 
 	while (node) {
 		struct callchain_node *child = rb_entry(node, struct callchain_node, rb_node);
-- 
2.1.3

Re: [PATCH] perf hists browser: Fix segfault when showing callchain

[Arnaldo Carvalho de Melo]

Em Wed, Dec 24, 2014 at 03:04:36PM +0900, Namhyung Kim escreveu:
> When perf report on TUI shows callchain it checks first node has
> siblings to determine whether it needs to print percentage value.  But
> it missed a case that first node is NULL.  So sometimes it segfaults
> like below:

Thanks, applied.
 
>   $ perf top -g
>   perf: Segmentation fault
>   -------- backtrace --------
>   perf[0x4fcefb]
>   /usr/lib/libc.so.6(+0x33b20)[0x7f2a35839b20]
>   perf(rb_next+0x8)[0x47d3d8]
>   perf[0x4f6058]
>   perf[0x4f833b]
>   perf[0x4f8610]
>   perf[0x4f209e]
>   perf(ui_browser__run+0x3a)[0x4f2e6a]
>   perf[0x4f94ee]
>   perf(perf_evlist__tui_browse_hists+0x94)[0x4fbbf4]
>   perf[0x444d10]
>   /usr/lib/libpthread.so.0(+0x7314)[0x7f2a37070314]
>   /usr/lib/libc.so.6(clone+0x6d)[0x7f2a358ee5bd]
> 
>   $ addr2line -e `which perf` 0x4f6058
>   /home/namhyung/project/linux/tools/perf/ui/browsers/hists.c:553
> 
> I don't know why the backtrace didn't print some symbols..
> 
> Fixes: 4087d11cd945 ("perf hists browser: Print overhead percent value for first-level callchain")
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/ui/browsers/hists.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> index e6bb04b5b09b..788506eef567 100644
> --- a/tools/perf/ui/browsers/hists.c
> +++ b/tools/perf/ui/browsers/hists.c
> @@ -550,7 +550,7 @@ static int hist_browser__show_callchain(struct hist_browser *browser,
>  	bool need_percent;
>  
>  	node = rb_first(root);
> -	need_percent = !!rb_next(node);
> +	need_percent = node && rb_next(node);
>  
>  	while (node) {
>  		struct callchain_node *child = rb_entry(node, struct callchain_node, rb_node);
> -- 
> 2.1.3

[tip:perf/urgent] perf hists browser: Fix segfault when showing callchain

[tip-bot for Namhyung Kim]

Commit-ID:  c09e31cc128cf1aec3a6cd47203508fbf0082873
Gitweb:     http://git.kernel.org/tip/c09e31cc128cf1aec3a6cd47203508fbf0082873
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Wed, 24 Dec 2014 15:04:36 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 8 Jan 2015 11:59:16 -0300

perf hists browser: Fix segfault when showing callchain

When perf report on TUI shows callchain it checks first node has
siblings to determine whether it needs to print percentage value.

But it missed a case that first node is NULL.  So sometimes it segfaults
like below:

  $ perf top -g
  perf: Segmentation fault
  -------- backtrace --------
  perf[0x4fcefb]
  /usr/lib/libc.so.6(+0x33b20)[0x7f2a35839b20]
  perf(rb_next+0x8)[0x47d3d8]
  perf[0x4f6058]
  perf[0x4f833b]
  perf[0x4f8610]
  perf[0x4f209e]
  perf(ui_browser__run+0x3a)[0x4f2e6a]
  perf[0x4f94ee]
  perf(perf_evlist__tui_browse_hists+0x94)[0x4fbbf4]
  perf[0x444d10]
  /usr/lib/libpthread.so.0(+0x7314)[0x7f2a37070314]
  /usr/lib/libc.so.6(clone+0x6d)[0x7f2a358ee5bd]

  $ addr2line -e `which perf` 0x4f6058
  /home/namhyung/project/linux/tools/perf/ui/browsers/hists.c:553

I don't know why the backtrace didn't print some symbols..

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Fixes: 4087d11cd945 ("perf hists browser: Print overhead percent value for first-level callchain")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1419401076-21700-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/ui/browsers/hists.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index e6bb04b..788506e 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -550,7 +550,7 @@ static int hist_browser__show_callchain(struct hist_browser *browser,
 	bool need_percent;
 
 	node = rb_first(root);
-	need_percent = !!rb_next(node);
+	need_percent = node && rb_next(node);
 
 	while (node) {
 		struct callchain_node *child = rb_entry(node, struct callchain_node, rb_node);