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Atomic test: Fix use after free 

SDL_SemPost() was called by the FIFO threads after the semaphore was
freed because the main thread actually synchronized on the
`writerRunning`/`readersRunning` count and not the semaphores itself.
This commit is contained in:
Joel Linn 2020-12-23 13:36:23 -08:00
parent 6267b95177
commit 2b040cebbe
1 changed files with 2 additions and 8 deletions
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10
test/testatomic.c
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@ -473,8 +473,6 @@ static SDL_bool DequeueEvent_Mutex(SDL_EventQueue *queue, SDL_Event *event)
static SDL_sem *writersDone; static SDL_sem *writersDone;
static SDL_sem *readersDone; static SDL_sem *readersDone;
static SDL_atomic_t writersRunning;
static SDL_atomic_t readersRunning;
typedef struct typedef struct
{ {
@ -525,7 +523,6 @@ static int SDLCALL FIFO_Writer(void* _data)
} }
} }
} }
SDL_AtomicAdd(&writersRunning, -1);
SDL_SemPost(writersDone); SDL_SemPost(writersDone);
return 0; return 0;
} }
@ -563,7 +560,6 @@ static int SDLCALL FIFO_Reader(void* _data)
} }
} }
} }
SDL_AtomicAdd(&readersRunning, -1);
SDL_SemPost(readersDone); SDL_SemPost(readersDone);
return 0; return 0;
} }
@ -627,7 +623,6 @@ static void RunFIFOTest(SDL_bool lock_free)
/* Start the readers first */ /* Start the readers first */
SDL_Log("Starting %d readers\n", NUM_READERS); SDL_Log("Starting %d readers\n", NUM_READERS);
SDL_zeroa(readerData); SDL_zeroa(readerData);
SDL_AtomicSet(&readersRunning, NUM_READERS);
for (i = 0; i < NUM_READERS; ++i) { for (i = 0; i < NUM_READERS; ++i) {
char name[64]; char name[64];
SDL_snprintf(name, sizeof (name), "FIFOReader%d", i); SDL_snprintf(name, sizeof (name), "FIFOReader%d", i);
@ -639,7 +634,6 @@ static void RunFIFOTest(SDL_bool lock_free)
/* Start up the writers */ /* Start up the writers */
SDL_Log("Starting %d writers\n", NUM_WRITERS); SDL_Log("Starting %d writers\n", NUM_WRITERS);
SDL_zeroa(writerData); SDL_zeroa(writerData);
SDL_AtomicSet(&writersRunning, NUM_WRITERS);
for (i = 0; i < NUM_WRITERS; ++i) { for (i = 0; i < NUM_WRITERS; ++i) {
char name[64]; char name[64];
SDL_snprintf(name, sizeof (name), "FIFOWriter%d", i); SDL_snprintf(name, sizeof (name), "FIFOWriter%d", i);
@ -650,7 +644,7 @@ static void RunFIFOTest(SDL_bool lock_free)
} }
/* Wait for the writers */ /* Wait for the writers */
while (SDL_AtomicGet(&writersRunning) > 0) { for (i = 0; i < NUM_WRITERS; ++i) {
SDL_SemWait(writersDone); SDL_SemWait(writersDone);
} }
@ -658,7 +652,7 @@ static void RunFIFOTest(SDL_bool lock_free)
SDL_AtomicSet(&queue.active, 0); SDL_AtomicSet(&queue.active, 0);
/* Wait for the readers */ /* Wait for the readers */
while (SDL_AtomicGet(&readersRunning) > 0) { for (i = 0; i < NUM_READERS; ++i) {
SDL_SemWait(readersDone); SDL_SemWait(readersDone);
} }