Bug 2536712 (CVE-2026-93135)

Summary: CVE-2026-93135 kernel: bpf: Reject programs with inlined helpers if JIT is not available
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF). When the Just-In-Time (JIT) compiler is unavailable or fails, BPF programs that use inlined helper functions are processed by the interpreter with unpatched helper identifiers. This incorrect processing can lead to an instruction alignment fault or a kernel panic, effectively causing a Denial of Service (DoS) to the system.
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Description OSIDB Bzimport 2026-09-17 19:15:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject programs with inlined helpers if JIT is not available

When an architecture (such as LoongArch, ARM64, and RISC-V) implements
bpf_jit_inlines_helper_call(), the verifier skips rewriting the helper
call offset (insn->imm) in bpf_do_misc_fixups(). This is because the
helper is expected to be inlined by the JIT compiler later. Therefore,
insn->imm remains as the raw helper enum ID.

However, if JIT is disabled at runtime (net.core.bpf_jit_enable=0) or
if JIT compilation fails dynamically (e.g., due to OOM), the program
falls back to the BPF interpreter.

When the interpreter executes (__bpf_call_base + insn->imm) with the
unpatched raw ID, it jumps into an invalid address space, triggering
an instruction alignment fault or a kernel panic.

Although these helpers have valid C implementations in the kernel, the
omission of offset rewriting makes runtime interpreter fallback fatal.

Fix this by setting 'prog->jit_required = 1' when helper call rewriting
is skipped for JIT inlining. This ensures that such programs are safely
rejected if JIT is not available, preventing the runtime kernel panic.
Comment 1 gkamathe 2026-09-18 18:22:56 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93135.mbox