From: Peter Zijlstra peterz@infradead.org
stable inclusion from stable-v5.10.133 commit 270de63cf4a380fe9942d3e0da599c0e966fad78 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5PTAS CVE: CVE-2022-29900,CVE-2022-23816,CVE-2022-29901
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 0b53c374b9eff2255a386f1f1cfb9a928e52a5ae upstream.
Utilize -mfunction-return=thunk-extern when available to have the compiler replace RET instructions with direct JMPs to the symbol __x86_return_thunk. This does not affect assembler (.S) sources, only C sources.
-mfunction-return=thunk-extern has been available since gcc 7.3 and clang 15.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Nick Desaulniers ndesaulniers@google.com Reviewed-by: Josh Poimboeuf jpoimboe@kernel.org Tested-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Borislav Petkov bp@suse.de [cascardo: RETPOLINE_CFLAGS is at Makefile] [cascardo: remove ANNOTATE_NOENDBR from __x86_return_thunk] Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Lin Yujun linyujun809@huawei.com Reviewed-by: Zhang Jianhua chris.zjh@huawei.com --- Makefile | 2 ++ arch/x86/include/asm/nospec-branch.h | 2 ++ arch/x86/lib/retpoline.S | 12 ++++++++++++ 3 files changed, 16 insertions(+)
diff --git a/Makefile b/Makefile index ebb503a59db2..963734589fe6 100644 --- a/Makefile +++ b/Makefile @@ -672,11 +672,13 @@ endif
ifdef CONFIG_CC_IS_GCC RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) +RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern) RETPOLINE_VDSO_CFLAGS := $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register) endif ifdef CONFIG_CC_IS_CLANG RETPOLINE_CFLAGS := -mretpoline-external-thunk RETPOLINE_VDSO_CFLAGS := -mretpoline +RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern) endif export RETPOLINE_CFLAGS export RETPOLINE_VDSO_CFLAGS diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index e791fe7e9de5..6eedd835613c 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -120,6 +120,8 @@ _ASM_PTR " 999b\n\t" \ ".popsection\n\t"
+extern void __x86_return_thunk(void); + #ifdef CONFIG_RETPOLINE
typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE]; diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index c013241d9188..01667ea9da02 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -66,3 +66,15 @@ SYM_CODE_END(__x86_indirect_thunk_array) #define GEN(reg) EXPORT_THUNK(reg) #include <asm/GEN-for-each-reg.h> #undef GEN + +/* + * This function name is magical and is used by -mfunction-return=thunk-extern + * for the compiler to generate JMPs to it. + */ +SYM_CODE_START(__x86_return_thunk) + UNWIND_HINT_EMPTY + ret + int3 +SYM_CODE_END(__x86_return_thunk) + +__EXPORT_THUNK(__x86_return_thunk)