This is a note to let you know that I've just added the patch titled objtool: Update Retpoline validation to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: objtool-update-retpoline-validation.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Tue Jul 12 05:06:57 PM CEST 2022 From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Tue, 14 Jun 2022 23:15:59 +0200 Subject: objtool: Update Retpoline validation From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> commit 9bb2ec608a209018080ca262f771e6a9ff203b6f upstream. Update retpoline validation with the new CONFIG_RETPOLINE requirement of not having bare naked RET instructions. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> [cascardo: conflict fixup at arch/x86/xen/xen-head.S] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/include/asm/nospec-branch.h | 6 ++++++ arch/x86/mm/mem_encrypt_boot.S | 2 ++ arch/x86/xen/xen-head.S | 1 + tools/objtool/check.c | 19 +++++++++++++------ 4 files changed, 22 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -76,6 +76,12 @@ .endm /* + * (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions + * vs RETBleed validation. + */ +#define ANNOTATE_UNRET_SAFE ANNOTATE_RETPOLINE_SAFE + +/* * JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple * indirect jmp/call which may be susceptible to the Spectre variant 2 * attack. --- a/arch/x86/mm/mem_encrypt_boot.S +++ b/arch/x86/mm/mem_encrypt_boot.S @@ -66,6 +66,7 @@ SYM_FUNC_START(sme_encrypt_execute) pop %rbp /* Offset to __x86_return_thunk would be wrong here */ + ANNOTATE_UNRET_SAFE ret int3 SYM_FUNC_END(sme_encrypt_execute) @@ -154,6 +155,7 @@ SYM_FUNC_START(__enc_copy) pop %r15 /* Offset to __x86_return_thunk would be wrong here */ + ANNOTATE_UNRET_SAFE ret int3 .L__enc_copy_end: --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -70,6 +70,7 @@ SYM_CODE_START(hypercall_page) .rept (PAGE_SIZE / 32) UNWIND_HINT_FUNC .skip 31, 0x90 + ANNOTATE_UNRET_SAFE RET .endr --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1894,8 +1894,9 @@ static int read_retpoline_hints(struct o } if (insn->type != INSN_JUMP_DYNAMIC && - insn->type != INSN_CALL_DYNAMIC) { - WARN_FUNC("retpoline_safe hint not an indirect jump/call", + insn->type != INSN_CALL_DYNAMIC && + insn->type != INSN_RETURN) { + WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret", insn->sec, insn->offset); return -1; } @@ -3229,7 +3230,8 @@ static int validate_retpoline(struct obj for_each_insn(file, insn) { if (insn->type != INSN_JUMP_DYNAMIC && - insn->type != INSN_CALL_DYNAMIC) + insn->type != INSN_CALL_DYNAMIC && + insn->type != INSN_RETURN) continue; if (insn->retpoline_safe) @@ -3244,9 +3246,14 @@ static int validate_retpoline(struct obj if (!strcmp(insn->sec->name, ".init.text") && !module) continue; - WARN_FUNC("indirect %s found in RETPOLINE build", - insn->sec, insn->offset, - insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); + if (insn->type == INSN_RETURN) { + WARN_FUNC("'naked' return found in RETPOLINE build", + insn->sec, insn->offset); + } else { + WARN_FUNC("indirect %s found in RETPOLINE build", + insn->sec, insn->offset, + insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); + } warnings++; } Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are queue-5.15/x86-sev-avoid-using-__x86_return_thunk.patch queue-5.15/x86-ftrace-use-alternative-ret-encoding.patch queue-5.15/objtool-re-add-unwind_hint_-save_restore.patch queue-5.15/x86-bugs-add-retbleed-ibpb.patch queue-5.15/x86-bugs-enable-stibp-for-jmp2ret.patch queue-5.15/x86-retpoline-cleanup-some-ifdefery.patch queue-5.15/kvm-vmx-flatten-__vmx_vcpu_run.patch queue-5.15/x86-kvm-vmx-make-noinstr-clean.patch queue-5.15/objtool-x86-replace-alternatives-with-.retpoline_sites.patch queue-5.15/x86-retbleed-add-fine-grained-kconfig-knobs.patch queue-5.15/x86-cpu-amd-add-spectral-chicken.patch queue-5.15/kvm-vmx-fix-ibrs-handling-after-vmexit.patch queue-5.15/kvm-vmx-prevent-guest-rsb-poisoning-attacks-with-eibrs.patch queue-5.15/x86-vsyscall_emu-64-don-t-use-ret-in-vsyscall-emulation.patch queue-5.15/x86-add-magic-amd-return-thunk.patch queue-5.15/x86-bugs-keep-a-per-cpu-ia32_spec_ctrl-value.patch queue-5.15/x86-objtool-create-.return_sites.patch queue-5.15/x86-alternative-handle-jcc-__x86_indirect_thunk_-reg.patch queue-5.15/x86-kvm-fix-setcc-emulation-for-return-thunks.patch queue-5.15/x86-retpoline-swizzle-retpoline-thunk.patch queue-5.15/x86-speculation-fix-firmware-entry-spec_ctrl-handling.patch queue-5.15/x86-retpoline-remove-unused-replacement-symbols.patch queue-5.15/x86-speculation-add-spectre_v2-ibrs-option-to-support-kernel-ibrs.patch queue-5.15/x86-xen-add-untrain_ret.patch queue-5.15/bpf-x86-respect-x86_feature_retpoline.patch queue-5.15/x86-undo-return-thunk-damage.patch queue-5.15/x86-entry-avoid-very-early-ret.patch queue-5.15/x86-entry-move-push_and_clear_regs-back-into-error_entry.patch queue-5.15/x86-retpoline-create-a-retpoline-thunk-array.patch queue-5.15/x86-asm-fix-register-order.patch queue-5.15/x86-speculation-fill-rsb-on-vmexit-for-ibrs.patch queue-5.15/objtool-add-entry-unret-validation.patch queue-5.15/objtool-shrink-struct-instruction.patch queue-5.15/kvm-vmx-convert-launched-argument-to-flags.patch queue-5.15/x86-bpf-use-alternative-ret-encoding.patch queue-5.15/x86-common-stamp-out-the-stepping-madness.patch queue-5.15/x86-bugs-split-spectre_v2_select_mitigation-and-spectre_v2_user_select_mitigation.patch queue-5.15/x86-bugs-report-intel-retbleed-vulnerability.patch queue-5.15/bpf-x86-simplify-computing-label-offsets.patch queue-5.15/x86-cpufeatures-move-retpoline-flags-to-word-11.patch queue-5.15/x86-speculation-fix-spec_ctrl-write-on-smt-state-change.patch queue-5.15/x86-retpoline-use-mfunction-return.patch queue-5.15/x86-xen-rename-sys-entry-points.patch queue-5.15/x86-bugs-optimize-spec_ctrl-msr-writes.patch queue-5.15/x86-bugs-report-amd-retbleed-vulnerability.patch queue-5.15/x86-static_call-use-alternative-ret-encoding.patch queue-5.15/x86-speculation-fix-rsb-filling-with-config_retpoline-n.patch queue-5.15/x86-asm-fixup-odd-gen-for-each-reg.h-usage.patch queue-5.15/x86-alternative-add-debug-prints-to-apply_retpolines.patch queue-5.15/x86-use-return-thunk-in-asm-code.patch queue-5.15/objtool-classify-symbols.patch queue-5.15/intel_idle-disable-ibrs-during-long-idle.patch queue-5.15/x86-retpoline-move-the-retpoline-thunk-declarations-to-nospec-branch.h.patch queue-5.15/x86-alternative-implement-.retpoline_sites-support.patch queue-5.15/x86-alternative-try-inline-spectre_v2-retpoline-amd.patch queue-5.15/x86-entry-remove-skip_r11rcx.patch queue-5.15/objtool-explicitly-avoid-self-modifying-code-in-.altinstr_replacement.patch queue-5.15/x86-speculation-use-cached-host-spec_ctrl-value-for-guest-entry-exit.patch queue-5.15/x86-bugs-add-amd-retbleed-boot-parameter.patch queue-5.15/x86-entry-add-kernel-ibrs-implementation.patch queue-5.15/objtool-treat-.text.__x86.-as-noinstr.patch queue-5.15/objtool-introduce-cfi-hash.patch queue-5.15/objtool-default-ignore-int3-for-unreachable.patch queue-5.15/objtool-update-retpoline-validation.patch