sonivox: prevent rejection of good but large MIDI files

A security patch that was trying to detect infinite loops
was accidentally rejecting very large MIDI files.
This is because there is a scanning pass that looks at the entire
file. That was generating a very high eventCount.
With this change, we do not check event counts during the scanning pass.

Bug: 112735915
Bug: 112575219
Bug: 68664359
Test: Generate a MIDI files with more than 50000 events.
Test: There are some in b/112735915 and b/112575219
Test: mmma frameworks/av/cmds/stagefright
Test: adb push out/target/product/marlin/system/bin/stagefright /system/bin/.
Test: adb shell stagefright -a /sdcard/Download/verybigfile.mid
Test: It should play correctly and not abort.
Change-Id: Iddf2f5b178e9ca3867b14fcd78d538023d79240d
Merged-In: Iddf2f5b178e9ca3867b14fcd78d538023d79240d
(cherry picked from commit 123051dd0271ac0f245cb88c38878c6b21880632)

1 files changed, 10 insertions, 5 deletions

diff --git a/arm-wt-22k/lib_src/eas_public.c b/arm-wt-22k/lib_src/eas_public.c
index d5316c5..1f2fe8a 100644
--- a/arm-wt-22k/lib_src/eas_public.c
+++ b/arm-wt-22k/lib_src/eas_public.c
@@ -1248,12 +1248,13 @@ static EAS_RESULT EAS_ParseEvents (S_EAS_DATA *pEASData, EAS_HANDLE pStream, EAS
     EAS_BOOL done;
     EAS_INT yieldCount = YIELD_EVENT_COUNT;
     EAS_U32 time = 0;
+
     // This constant is the maximum number of events that can be processed in a single time slice.
     // A typical ringtone will contain a few events per time slice.
     // Extremely dense ringtones might go up to 50 events.
     // If we see this many events then the file is probably stuck in an infinite loop
-    // and should be aborted.  In our testing, it took less than 100 msec to hit this limit.
-    static const EAS_INT MAX_EVENT_COUNT = 50000;
+    // and should be aborted.
+    static const EAS_INT MAX_EVENT_COUNT = 100000;
     EAS_INT eventCount = 0;
 
     /* does this parser have a time function? */
@@ -1309,10 +1310,14 @@ static EAS_RESULT EAS_ParseEvents (S_EAS_DATA *pEASData, EAS_HANDLE pStream, EAS
                         return result;
                     }
                 }
-                // An infinite loop within a single frame of a ringtone file can cause this function
+
+                // An infinite loop within a ringtone file can cause this function
                 // to loop forever.  Try to detect that and return an error.
-                if (++eventCount >= MAX_EVENT_COUNT) {
-                    ALOGE("%s() aborting, %d events without advancing to next frame",
+                // Only check when playing. Otherwise a very large file could be rejected
+                // when scanning the entire file in a single call to this function.
+                // OTA files will only do infinite loops when in eParserModePlay.
+                if (++eventCount >= MAX_EVENT_COUNT && parseMode == eParserModePlay) {
+                    ALOGE("%s() aborting, %d events. Infinite loop in song file?!",
                             __func__, eventCount);
                     android_errorWriteLog(0x534e4554, "68664359");
                     return EAS_ERROR_FILE_POS;