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games/gzdoom: fix wildmidi crash

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get_patch_data() may recurse on itself, which is not OK to do while
using std::lock_guard<>.  Move the contents of get_patch_data() to a
get_patch_data_locked() that may recurse on itself.

This is a direct commit to quarterly, as this has since been fixed by
the version present in main.  Specifically, a later refactoring ends up
dropping the patch_lock entirely after get_patch_data() and friends are
pushed into an Instruments class anyways.

Based on triage work and an initial patch by wpaul@.
This commit is contained in:
Kyle Evans 2021-12-15 23:36:04 -06:00
parent 0a7ee2e927
commit 446e0f2e6c
1 changed files with 49 additions and 0 deletions
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49
games/gzdoom/files/patch-src_sound_wildmidi_wildmidi__lib.cpp Normal file
View file

@ -0,0 +1,49 @@
--- src/sound/wildmidi/wildmidi_lib.cpp.orig 2019-05-04 19:58:35 UTC
+++ src/sound/wildmidi/wildmidi_lib.cpp
@@ -1318,11 +1318,9 @@ static int load_sample(struct _patch *sample_patch) {
}
static struct _patch *
-get_patch_data(unsigned short patchid) {
+get_patch_data_locked(unsigned short patchid) {
struct _patch *search_patch;
- std::lock_guard<std::mutex> lock(patch_lock);
-
search_patch = patch[patchid & 0x007F];
if (search_patch == NULL) {
@@ -1335,12 +1333,32 @@ get_patch_data(unsigned short patchid) {
}
search_patch = search_patch->next;
}
if ((patchid >> 8) != 0) {
- return (get_patch_data(patchid & 0x00FF));
+ return (get_patch_data_locked(patchid & 0x00FF));
}
return NULL;
}
+static struct _patch *
+get_patch_data(unsigned short patchid) {
+ struct _patch *patch;
+
+ /*
+ * Uh, hey, no, sorry pal, you can't use this
+ * construction here. This function can call itself
+ * recursively, which means you will recursively
+ * try to acquire the patch_lock mutex, which is
+ * not allowed with lock_guard.
+ */
+
+/* std::lock_guard<std::mutex> lock(patch_lock); */
+
+ patch_lock.lock();
+ patch = get_patch_data_locked(patchid);
+ patch_lock.unlock();
+ return (patch);
+}
+
static void load_patch(struct _mdi *mdi, unsigned short patchid) {
unsigned int i;
struct _patch *tmp_patch = NULL;