DivestOS/Patches/Common/android_external_hardened_malloc/0003-Broken_Audio.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Thu, 28 May 2020 20:19:14 -0400
Subject: [PATCH] workaround for audio service sorting bug

---
 h_malloc.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/h_malloc.c b/h_malloc.c
index 6c3b148..4090b0c 100644
--- a/h_malloc.c
+++ b/h_malloc.c
@@ -83,6 +83,7 @@ static union {
         bool zero_on_free;
         bool purge_slabs;
         bool region_quarantine_protect;
+        bool slot_randomize;
     };
     char padding[PAGE_SIZE];
 } ro __attribute__((aligned(PAGE_SIZE)));
@@ -386,7 +387,7 @@ static u64 get_mask(size_t slots) {
 }
 
 static size_t get_free_slot(struct random_state *rng, size_t slots, const struct slab_metadata *metadata) {
-    if (SLOT_RANDOMIZE) {
+    if (ro.slot_randomize) {
         // randomize start location for linear search (uniform random choice is too slow)
         size_t random_index = get_random_u16_uniform(rng, slots);
         size_t first_bitmap = random_index / U64_WIDTH;
@@ -1218,6 +1219,12 @@ COLD static void handle_bugs(void) {
         ro.purge_slabs = false;
         ro.region_quarantine_protect = false;
     }
+
+    // DeviceDescriptor sorting wrongly relies on malloc addresses
+    const char audio_service[] = "/system/bin/audioserver";
+    if (strcmp(audio_service, path) == 0) {
+        ro.slot_randomize = false;
+    }
 }
 
 static struct mutex init_lock = MUTEX_INITIALIZER;
@@ -1238,6 +1245,7 @@ COLD static void init_slow_path(void) {
     ro.purge_slabs = true;
     ro.zero_on_free = ZERO_ON_FREE;
     ro.region_quarantine_protect = true;
+    ro.slot_randomize = SLOT_RANDOMIZE;
     handle_bugs();
 
     if (unlikely(sysconf(_SC_PAGESIZE) != PAGE_SIZE)) {