Security vulnerabilities and automated fixes for null pointer dereference issues
5 posts found
The XCB image-reply handler in the screen-streaming bridge allocated a buffer with `malloc()` and immediately wrote to it with `memset()` and `memcpy()` without checking for allocation failure. Under memory pressure, this produces a null-pointer dereference that crashes the process, turning a resource-exhaustion condition into an immediate denial of service. The fix adds a NULL check that frees the intermediate reply and returns early instead of writing to invalid memory.
A critical memory safety vulnerability was discovered in `bench/tokenizer/tokenizer.c` where `malloc()` was called without checking its return value before passing the pointer to `memcpy()`. If allocation fails and `malloc()` returns NULL, the subsequent `memcpy()` writes to address zero, causing heap corruption or potential arbitrary code execution. The fix adds a single NULL check immediately after allocation, exiting cleanly on failure rather than proceeding with a dangerously invalid pointer
A critical vulnerability in `email/receive.cpp` allowed attackers to trigger a buffer overflow by sending crafted emails with large payloads. The `writefunc()` callback failed to validate that `realloc()` succeeded before writing to the reallocated pointer, risking NULL pointer dereference and potential code execution. The fix adds a simple bounds check that validates the realloc result before use.
A critical NULL pointer dereference vulnerability in the ESP8266 firmware's `user_interface.c` allowed attackers to crash devices by exhausting the limited 80KB heap memory. The `wifi_station_set_default_hostname()` function's `os_malloc` call lacked a proper NULL guard, causing `ets_sprintf` to write to address 0 when allocation failed. The fix corrected a logic inversion in the NULL check condition.
A high-severity NULL pointer dereference vulnerability was discovered and fixed in embedded eMMC storage handling code, where unchecked `malloc` and `calloc` return values could allow an attacker with a crafted eMMC image to crash the host process. The fix adds proper NULL checks after every memory allocation, preventing exploitation through maliciously oversized partition size fields. This type of vulnerability is surprisingly common in systems-level C code and serves as a reminder that defensi