An anonymous reader quotes a report from ZDNet: For years, there’s been a known security vulnerability hiding in the GNU C Library (glibc). This library, which is critical for Linux and many other operating systems and programs, had a dynamic memory management security hole that could be used for denial of service (DoS) attacks. Now, the security company, Check Point, has issued an open-source patch, which will make it much more difficult to exploit this memory allocation (malloc) problem. Check Point re-encountered this known problem when it discovered that so-called smart light bulbs could be used to hack into networks by exploiting unprotected single-linked-lists. The double-linked-list version of this problem had been fixed back in 2005 with Safe-Unlinking. But, the single-linked-list version, which is present in the memory primitive functions Fast-Bins and Thread Cache (TCache), remained vulnerable.
Now, the fix is in for this problem. This new built-in security mechanism is called Safe-Linking. It protects malloc by signing its single-linked-list pointers with random numbers derived from Linux’s Address Space Layout Randomization (ASLR) functionality. Combined with memory chunk alignment integrity checks, it protects the memory pointers from hijacking attempts and thus the system itself. The patch is now being integrated with the most common standard C library implementation, glibc. Safe-Linking will be released in glibc 2.32 in August 2020. It’s already up and running in glibc’s popular embedded counterpart: uClibc-NG.
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