Live › vulnerability › CVE-2026-99092
Go to dashboardOn RISC-V kernels built without CONFIG_STRICT_MODULE_RWX, writing BPF JIT code to read-only vmalloc memory faults, so the BPF program is left un-JITed. The sources describe a robustness failure rather than an attacker gaining code execution or data.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-26 16:02 UTC. All times on this page are UTC.
RISC-V Linux systems where BPF JIT is used and CONFIG_STRICT_MODULE_RWX is disabled, including the CONFIG_MODULES=y case where that option is off. Systems on x86, arm64, or other architectures are not described as affected. Kernels with strict module RWX enabled are not described as affected.
No product ranges from the sources yet.
CONFIG_STRICT_MODULE_RWX to n, for example with grep STRICT_MODULE_RWX /boot/config-$(uname -r)uname -m returning riscv64CONFIG_BPF_JIT is enabled in the same config fileEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
riscv: patch: fix handling of bpf-jit execmem addresses
Commit 8718e5a3090b ("riscv: patch: skip fixmap mapping when kernel text is already writable") gated the core_kernel_text() branch of patch_map() on CONFIG_STRICT_KERNEL_RWX, and explicitly left the vmalloc branch unchanged. That branch has a separate problem.
That branch only creates a temporary writable fixmap alias when CONFIG_STRICT_MODULE_RWX is enabled, and otherwise assumes the target is directly writable and returns the address unchanged. That assumption no longer holds: bpf_prog_pack_alloc calls set_memory_rox() on every pack unconditionally in alloc_new_pack(), independently of any CONFIG_STRICT_*_RWX option, so BPF text in the vmalloc area is read-only regardless of what CONFIG_STRICT_MODULE_RWX says.
With CONFIG_STRICT_MODULE_RWX=n, patch_map() returns the read-only address directly, the subsequent copy_to_kernel_nofault() takes a page fault and returns -EFAULT. bpf_arch_text_copy() turns that into -EINVAL, which propagates through bpf_jit_binary_pack_finalize() to the WARN_ON() in bpf_int_jit_compile() and leaves the program un-JITed.
Note that BPF cannot be fixed the way kprobes was in commit bdc46e507b59 ("riscv: mm: make EXECMEM_KPROBES writable without CONFIG_STRICT_MODULE_RWX"). EXECMEM_BPF is already PAGE_KERNEL, i.e. writable at allocation time; the read-only mapping is established afterwards by generic code in alloc_new_pack(), which arch code cannot influence. The only place this can be handled is patch_map().
This is the same problem that was fixed on arm64 by commit b1480ed230ac ("arm64: patching: fix handling of execmem addresses"), and the fix is the same: CONFIG_EXECMEM is what actually tracks whether the vmalloc area can hold executable memory that needs a temporary alias to be written. CONFIG_BPF_JIT, CONFIG_KPROBES and CONFIG_MODULES all select it.
Note that this is not limited to CONFIG_MODULES=n. Unlike arm64, riscv selects CONFIG_ARCH_OPTIONAL_KERNEL_RWX, so CONFIG_STRICT_MODULE_RWX can be disabled with CONFIG_MODULES=y as well, and the bug is reachable in that configuration too.
The !CONFIG_MMU build is unaffected: it has its own __patch_insn_set() and __patch_insn_write() implementations and never calls patch_map().
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