[iOS] Incorrect Memory Leak Detection

[FredericJacobs]

The following Objective-C code incorrectly results in a error: MEMORY_LEAK memory dynamically allocated to buffer by call to malloc() at line X, column X is not reachable after line X, column X.

void* buffer = malloc(bufferSize);
return [NSData dataWithBytesNoCopy:buffer length:bytesDecrypted freeWhenDone:YES];

The buffer is passed to the returned NSData object and will be deallocated when the NSData instance will be.

[dulmarod]

Hi,
That is a real leak. The documentation of Apple also says that if the NSData object doesn't get created then the method will return nil. In that case the buffer will be leaked.

[FredericJacobs]

Oh right, thanks.
Got an assertion for that but good point.

[dflems]

@dulmarod: I still see this as a MEMORY_LEAK after doing a nil-check. Is there a way to silence this? (using infer 0.12.0)

uint8_t *buffer = malloc(length);
...
NSData *data = [NSData dataWithBytesNoCopy:buffer length:length freeWhenDone:YES];
if (!data) {
    free(buffer);
}
return data;

[dulmarod]

There isn't a way to silence individual bugs at the moment.