AZL-95892

Multiple Use-After-Free vulnerabilities were found in the addarchiveelement function in ld/ldmain.c of the GNU linker (ld), a component of binutils. The root cause is that pluginmaybeclaim() in ld/plugin.c frees the original BFD object via bfdclose/bfddeletebfd when entry->thebfd->myarchive == NULL, but the caller retains both the original abfd parameter and a shallow copy (originput.thebfd) as dangling pointers. These dangling pointers are subsequently dereferenced at three distinct locations in addarchiveelement:

1. Line ~1442: accessing abfd->myarchive via bfdusrdata(abfd->my_archive)
2. Line ~1493: multiple accesses to abfd and abfd->myarchive in a conditional check and bfdget_filename call
3. Line ~1525: dereferencing the shallow copy originput.thebfd->my_archive in trace/verbose logging

The vulnerability is triggered when LTO plugins are active (linkinfo.ltopluginactive is true) and the input object has abfd->myarchive == NULL, which is a valid state for standalone object files. Red Hat builds binutils with --enable-plugins and --enable-lto, confirming the vulnerable code path is compiled in and reachable.

An attacker who can supply a crafted object or archive file to a build process using LTO-enabled linking could exploit this flaw to cause a denial of service (linker crash via segmentation fault). Arbitrary code execution is theoretically possible through heap manipulation but is substantially mitigated by hardening measures including stack protector, FORTIFY_SOURCE, ASLR, and PIE.

The attack surface is limited to build-time environments — the linker is a development tool not exposed in production runtime. The most realistic exploitation scenario is a supply chain attack introducing a crafted object file as a build dependency in CI/CD pipelines or development environments.