From b49414ea5da073042aab753a4fd9fd05fa5bb8d5 Mon Sep 17 00:00:00 2001 From: Caleb Connolly Date: Tue, 2 Nov 2021 18:56:21 +0000 Subject: mixer: fix index underflow when index=0 In mixer_get_ctl_by_name_and_index(), the post-fix decrement means that the index will be decremented after the comparison, but before the return, leading to an unsigned integer underflow. This causes a crash on platforms with -fsanitize=integer enabled. Fix this by avoiding decrementing index until after the return. Change-Id: I25a17ced4185bdebd500285bd30b342b16b4ac12 --- src/mixer.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/mixer.c b/src/mixer.c index 5581e5d..b4d96fd 100644 --- a/src/mixer.c +++ b/src/mixer.c @@ -732,9 +732,13 @@ struct mixer_ctl *mixer_get_ctl_by_name_and_index(struct mixer *mixer, ctl = grp->ctl; for (n = 0; n < grp->count; n++) - if (!strcmp(name, (char*) ctl[n].info.id.name)) - if (index-- == 0) + if (!strcmp(name, (char*) ctl[n].info.id.name)) { + if (index == 0) { return ctl + n; + } else { + index--; + } + } } #ifdef TINYALSA_USES_PLUGINS @@ -743,9 +747,13 @@ struct mixer_ctl *mixer_get_ctl_by_name_and_index(struct mixer *mixer, ctl = grp->ctl; for (n = 0; n < grp->count; n++) - if (!strcmp(name, (char*) ctl[n].info.id.name)) - if (index-- == 0) + if (!strcmp(name, (char*) ctl[n].info.id.name)) { + if (index == 0) { return ctl + n; + } else { + index--; + } + } } #endif return NULL; -- cgit v1.2.3