CVE-2026-64508

01/Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Support for hardening against JIT spraying The BPF JIT allocator packs many small programs into larger executable allocations and reuses space within those allocations as programs are loaded and freed. When fresh code is written into space that a previous program occupied, an indirect jump into the new program can reuse a branch prediction left behind by the old one. Flush the indirect branch predictors before reusing JIT memory so that indirect jumps into a newly written program don't reuse predictions from an old program that occupied the same space. Introduce bpf_arch_pred_flush_enabled static key and bpf_arch_pred_flush static call for flushing the branch predictors on JIT memory reuse. Architectures that need a flush, can update it to a predictor flush function. By default, its a NOP and does not emit any CALL. Allocations larger than a pack are not covered by this flush. That is safe because cBPF programs (the unprivileged attack surface) are bounded well below a pack size. Issue a warning if this assumption is ever violated while the flush is active.

02/Affected products

linux: linux kernel

03/References6

• git.kernel.org/stable/c/1fbafd5235ca897b322161659ebe8ba651b00b3b Patch
• git.kernel.org/stable/c/6e52c240c43a601b681e3a4e58fc5685114d4726 Patch
• git.kernel.org/stable/c/7a6c171c6a1ac6d1509752dac131d941a3de0b37 Patch
• git.kernel.org/stable/c/8ff183ee4d8c452960df58175a094828c0513b2e Patch
• git.kernel.org/stable/c/96cce16e26dd02a8678f1e87f88a4b5cdb63b995 Patch
• git.kernel.org/stable/c/eed774da601268dae674e14d54a15e3624691f52 Patch