Fix integer sanitizer in audio_route_update_path.

Calculating i could sometimes cause an unsigned integer overflow, which
led to runtime errors on integer sanitized builds.

 runtime error: unsigned integer overflow: 0 - 1 cannot be represented in
 type 'unsigned int'

This refactors the loop to avoid the overflow.

Bug: 30969751
Test: Compiles and device boots.
Change-Id: I468d064eda5213fd773a094412cd669fc23617dc

diff --git a/audio_route/audio_route.c b/audio_route/audio_route.c
index f619065..700af61 100644 (file)
--- a/audio_route/audio_route.c
+++ b/audio_route/audio_route.c
@@ -784,7 +784,6 @@ int audio_route_reset_path(struct audio_route *ar, const char *name)
 static int audio_route_update_path(struct audio_route *ar, const char *name, bool reverse)
 {
     struct mixer_path *path;
-    int32_t i, end;
     unsigned int j;
 
     if (!ar) {
@@ -798,14 +797,12 @@ static int audio_route_update_path(struct audio_route *ar, const char *name, boo
         return -1;
     }
 
-    i = reverse ? (path->length - 1) : 0;
-    end = reverse ? -1 : (int32_t)path->length;
 
-    while (i != end) {
+    for (size_t i = 0; i < path->length; ++i) {
         unsigned int ctl_index;
         enum mixer_ctl_type type;
 
-        ctl_index = path->setting[i].ctl_index;
+        ctl_index = path->setting[reverse ? path->length - 1 - i : i].ctl_index;
 
         struct mixer_state * ms = &ar->mixer_state[ctl_index];
 
@@ -836,8 +833,6 @@ static int audio_route_update_path(struct audio_route *ar, const char *name, boo
                 break;
             }
         }
-
-        i = reverse ? (i - 1) : (i + 1);
     }
     return 0;
 }