2021-05-31 21:34:54

by Riccardo Mancini

Subject: [PATCH] perf: fix segfault when wrong option for --debug is provided

The command `perf --debug record` causes a segfault instead of notifying
the user of the unrecognized option for --debug (the correct syntax would
be `perf --debug verbose=2 record`).

The bug is caused by a call to pr_err before debug_file (debug.c:34) is
set via perf_debug_setup(). It has been introduced in
commit 8abceacff87d ("perf debug: Add debug_set_file function").

This patch resolves the bug by calling perf_debug_setup earlier in the
main, so that debug_file is set to stderr before any call to a debug
printing function is made.

Signed-off-by: Riccardo Mancini <[email protected]>
---
tools/perf/perf.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 20cb91ef06ffc..cffbab2d085a7 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -448,6 +448,7 @@ int main(int argc, const char **argv)
pager_init(PERF_PAGER_ENVIRONMENT);

libperf_init(libperf_print);
+ perf_debug_setup();

cmd = extract_argv0_path(argv[0]);
if (!cmd)
@@ -531,8 +532,6 @@ int main(int argc, const char **argv)
*/
pthread__block_sigwinch();

- perf_debug_setup();
-
while (1) {
static int done_help;

--
2.23.0

2021-06-01 13:38:41

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH] perf: fix segfault when wrong option for --debug is provided

Em Mon, May 31, 2021 at 11:28:28PM +0200, Riccardo Mancini escreveu:
> The command `perf --debug record` causes a segfault instead of notifying
> the user of the unrecognized option for --debug (the correct syntax would
> be `perf --debug verbose=2 record`).
>
> The bug is caused by a call to pr_err before debug_file (debug.c:34) is
> set via perf_debug_setup(). It has been introduced in
> commit 8abceacff87d ("perf debug: Add debug_set_file function").
>
> This patch resolves the bug by calling perf_debug_setup earlier in the
> main, so that debug_file is set to stderr before any call to a debug
> printing function is made.

Ian fixed this earlier and it is already even upstream:

https://git.kernel.org/torvalds/c/c59870e2110e1229a6e4

Thanks,

- Arnaldo

> Signed-off-by: Riccardo Mancini <[email protected]>
> ---
> tools/perf/perf.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/tools/perf/perf.c b/tools/perf/perf.c
> index 20cb91ef06ffc..cffbab2d085a7 100644
> --- a/tools/perf/perf.c
> +++ b/tools/perf/perf.c
> @@ -448,6 +448,7 @@ int main(int argc, const char **argv)
> pager_init(PERF_PAGER_ENVIRONMENT);
>
> libperf_init(libperf_print);
> + perf_debug_setup();
>
> cmd = extract_argv0_path(argv[0]);
> if (!cmd)
> @@ -531,8 +532,6 @@ int main(int argc, const char **argv)
> */
> pthread__block_sigwinch();
>
> - perf_debug_setup();
> -
> while (1) {
> static int done_help;
>
> --
> 2.23.0
>

--

- Arnaldo