Greetings,
I came across a memory allocation within the EventHub.cpp that I think
can potentially leak and even cause a runtime error. The code is bit
different in Gingerbread and Froyo but both have the same problem.
Here is the snippet from the Gingerbread:
int EventHub::openDevice(const char *deviceName) {
...
x1) new_mFDs = (pollfd*)realloc(mFDs, sizeof(mFDs[0]) * (mFDCount +
1));
x2) new_devices = (device_t**)realloc(mDevices, sizeof(mDevices[0])
* (mFDCount + 1));
x3) if (new_mFDs == NULL || new_devices == NULL) {
x4) LOGE("out of memory");
x6) return -1;
x7) }
x8) mFDs = new_mFDs;
x9) mDevices = new_devices;
...
}
new_mFDs is a local pointer. Consider this scenario: memory is
allocated successfully at line x1, but the allocation at line x2
fails. Then, the function returns without talking
care of the newly allocated new_mFDs (the new pointer is saved at line
x8.) However, this is more serious that a memory leak; this is also a
dangling reference problem. Consider the case that (no matter how
unlikely) the memory manager cannot extend the memory block and
therefore allocates a new bigger block somewhere in the memory
and copies the old block. ( Then line x2 fails and the function
returns.) what happens is that the newly allocated block leaks and the
old pointer (mFDs) is a dangling reference
that we are holding on to and using everywhere, which most probably
would crash the process.
This was my observation and I hope I can get some feedback on this.
Thanks
--Hossein
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