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| Started by | Chris Phlipot <cphlipot0@gmail.com> |
|---|---|
| First post | 2016-04-20 04:40 +0200 |
| Last post | 2016-04-27 17:40 +0200 |
| Articles | 3 — 3 participants |
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[PATCH] perf script: fix segfault when printing callchains using builtin-script Chris Phlipot <cphlipot0@gmail.com> - 2016-04-20 04:40 +0200
Re: [PATCH] perf script: fix segfault when printing callchains using builtin-script Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-20 05:10 +0200
[tip:perf/core] perf script: Fix segfault when printing callchains tip-bot for Chris Phlipot <tipbot@zytor.com> - 2016-04-27 17:40 +0200
| From | Chris Phlipot <cphlipot0@gmail.com> |
|---|---|
| Date | 2016-04-20 04:40 +0200 |
| Subject | [PATCH] perf script: fix segfault when printing callchains using builtin-script |
| Message-ID | <rpQdz-yF-5@gated-at.bofh.it> |
This fixes a bug caused by an unitialized callchain cursor. The crash
frist appeared in:
6f736735e30f ("perf evsel: Require that callchains be resolved before
calling fprintf_{sym,callchain}")
The callchain cursor is a struct that contains pointers, that when
uninitialized will cause unpredictable behavior (usually a crash)
when trying to append to the callchain.
The existing implementation has the following issues:
1. The callchain cursor used is not initialized, resulting in
unpredictable behavior when used.
2. The cursor is declared on the stack. Even if it is properly initalized,
the implmentation will leak memory when the function returns,
since all the references to the callchain_nodes allocated by
callchain_cursor_append will be lost when the cursor goes out of
scope.
3. Storing the cursor on the stack is inefficient. Even if memory is
properly freed when it goes out of scope, a performance penalty
will be incurred due to reallocation of callchain nodes.
callchain_cursor_append is designed to avoid these reallocations
when an existing cursor is reused.
This patch fixes the crash by replacing cursor_callchain with a reference
to the global callchain_cursor which also resolves all 3 issues mentioned
above.
How to reproduce the crash:
$ perf record --call-graph=dwarf stress -t 1 -c 1
$ perf script > /dev/null
Segfault
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
---
tools/perf/builtin-script.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 5099740..f43b0c6 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -570,12 +570,12 @@ static void print_sample_bts(struct perf_sample *sample,
/* print branch_from information */
if (PRINT_FIELD(IP)) {
unsigned int print_opts = output[attr->type].print_ip_opts;
- struct callchain_cursor *cursor = NULL, cursor_callchain;
+ struct callchain_cursor *cursor = NULL;
if (symbol_conf.use_callchain && sample->callchain &&
- thread__resolve_callchain(al->thread, &cursor_callchain, evsel,
+ thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
sample, NULL, NULL, scripting_max_stack) == 0)
- cursor = &cursor_callchain;
+ cursor = &callchain_cursor;
if (cursor == NULL) {
putchar(' ');
@@ -789,12 +789,12 @@ static void process_event(struct perf_script *script,
printf("%16" PRIu64, sample->weight);
if (PRINT_FIELD(IP)) {
- struct callchain_cursor *cursor = NULL, cursor_callchain;
+ struct callchain_cursor *cursor = NULL;
if (symbol_conf.use_callchain && sample->callchain &&
- thread__resolve_callchain(al->thread, &cursor_callchain, evsel,
+ thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
sample, NULL, NULL, scripting_max_stack) == 0)
- cursor = &cursor_callchain;
+ cursor = &callchain_cursor;
putchar(cursor ? '\n' : ' ');
sample__fprintf_sym(sample, al, 0, output[attr->type].print_ip_opts, cursor, stdout);
--
2.7.4
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| From | Arnaldo Carvalho de Melo <acme@kernel.org> |
|---|---|
| Date | 2016-04-20 05:10 +0200 |
| Subject | Re: [PATCH] perf script: fix segfault when printing callchains using builtin-script |
| Message-ID | <rpQGB-12v-9@gated-at.bofh.it> |
| In reply to | #1383008 |
Em Tue, Apr 19, 2016 at 07:32:11PM -0700, Chris Phlipot escreveu:
> This fixes a bug caused by an unitialized callchain cursor. The crash
> frist appeared in:
> 6f736735e30f ("perf evsel: Require that callchains be resolved before
> calling fprintf_{sym,callchain}")
>
> The callchain cursor is a struct that contains pointers, that when
> uninitialized will cause unpredictable behavior (usually a crash)
> when trying to append to the callchain.
>
> The existing implementation has the following issues:
> 1. The callchain cursor used is not initialized, resulting in
> unpredictable behavior when used.
> 2. The cursor is declared on the stack. Even if it is properly initalized,
> the implmentation will leak memory when the function returns,
> since all the references to the callchain_nodes allocated by
> callchain_cursor_append will be lost when the cursor goes out of
> scope.
> 3. Storing the cursor on the stack is inefficient. Even if memory is
> properly freed when it goes out of scope, a performance penalty
> will be incurred due to reallocation of callchain nodes.
> callchain_cursor_append is designed to avoid these reallocations
> when an existing cursor is reused.
>
> This patch fixes the crash by replacing cursor_callchain with a reference
> to the global callchain_cursor which also resolves all 3 issues mentioned
> above.
>
> How to reproduce the crash:
> $ perf record --call-graph=dwarf stress -t 1 -c 1
> $ perf script > /dev/null
> Segfault
My bad, applying the patch, thanks!
- Arnaldo
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| From | tip-bot for Chris Phlipot <tipbot@zytor.com> |
|---|---|
| Date | 2016-04-27 17:40 +0200 |
| Subject | [tip:perf/core] perf script: Fix segfault when printing callchains |
| Message-ID | <rszJi-3tA-77@gated-at.bofh.it> |
| In reply to | #1383008 |
Commit-ID: e557b674a9470dae99916be6105e6780b3a072ca
Gitweb: http://git.kernel.org/tip/e557b674a9470dae99916be6105e6780b3a072ca
Author: Chris Phlipot <cphlipot0@gmail.com>
AuthorDate: Tue, 19 Apr 2016 19:32:11 -0700
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 25 Apr 2016 12:49:17 -0300
perf script: Fix segfault when printing callchains
This fixes a bug caused by an unitialized callchain cursor. The crash
frist appeared in:
6f736735e30f ("perf evsel: Require that callchains be resolved before
calling fprintf_{sym,callchain}")
The callchain cursor is a struct that contains pointers, that when
uninitialized will cause unpredictable behavior (usually a crash)
when trying to append to the callchain.
The existing implementation has the following issues:
1. The callchain cursor used is not initialized, resulting in
unpredictable behavior when used.
2. The cursor is declared on the stack. Even if it is properly initalized,
the implmentation will leak memory when the function returns,
since all the references to the callchain_nodes allocated by
callchain_cursor_append will be lost when the cursor goes out of
scope.
3. Storing the cursor on the stack is inefficient. Even if memory is
properly freed when it goes out of scope, a performance penalty
will be incurred due to reallocation of callchain nodes.
callchain_cursor_append is designed to avoid these reallocations
when an existing cursor is reused.
This patch fixes the crash by replacing cursor_callchain with a reference
to the global callchain_cursor which also resolves all 3 issues mentioned
above.
How to reproduce the crash:
$ perf record --call-graph=dwarf stress -t 1 -c 1
$ perf script > /dev/null
Segfault
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 6f736735e30f ("perf evsel: Require that callchains be resolved before calling fprintf_{sym,callchain}")
Link: http://lkml.kernel.org/r/1461119531-2529-1-git-send-email-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-script.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 5099740..f43b0c6 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -570,12 +570,12 @@ static void print_sample_bts(struct perf_sample *sample,
/* print branch_from information */
if (PRINT_FIELD(IP)) {
unsigned int print_opts = output[attr->type].print_ip_opts;
- struct callchain_cursor *cursor = NULL, cursor_callchain;
+ struct callchain_cursor *cursor = NULL;
if (symbol_conf.use_callchain && sample->callchain &&
- thread__resolve_callchain(al->thread, &cursor_callchain, evsel,
+ thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
sample, NULL, NULL, scripting_max_stack) == 0)
- cursor = &cursor_callchain;
+ cursor = &callchain_cursor;
if (cursor == NULL) {
putchar(' ');
@@ -789,12 +789,12 @@ static void process_event(struct perf_script *script,
printf("%16" PRIu64, sample->weight);
if (PRINT_FIELD(IP)) {
- struct callchain_cursor *cursor = NULL, cursor_callchain;
+ struct callchain_cursor *cursor = NULL;
if (symbol_conf.use_callchain && sample->callchain &&
- thread__resolve_callchain(al->thread, &cursor_callchain, evsel,
+ thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
sample, NULL, NULL, scripting_max_stack) == 0)
- cursor = &cursor_callchain;
+ cursor = &callchain_cursor;
putchar(cursor ? '\n' : ' ');
sample__fprintf_sym(sample, al, 0, output[attr->type].print_ip_opts, cursor, stdout);
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