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

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

[Riccardo Mancini]

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 <rickyman7@gmail.com>
---
 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

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

[Arnaldo Carvalho de Melo]

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 <rickyman7@gmail.com>
> ---
>  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