fd5e262706
When -fpatchable-function-entry is used to emit prefix nops before functions, KCFI assumes all indirectly called functions have the same number of prefix nops, because the nops are emitted between the KCFI type hash and the function entry. However, as patchable-function-prefix is a function attribute set by Clang, functions later synthesized by LLVM don't inherit this attribute and end up not having prefix nops. One of these functions is asan.module_ctor, which the Linux kernel ends up calling indirectly when KASAN is enabled. In order to avoid tripping KCFI, save the expected prefix offset to a module flag, and use it when we're setting KCFI type for the relevant synthesized functions. Link: https://github.com/ClangBuiltLinux/linux/issues/1742 Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D141172
61 lines
2.2 KiB
C
61 lines
2.2 KiB
C
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -o - %s | FileCheck %s
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -x c++ -o - %s | FileCheck %s
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -fpatchable-function-entry-offset=3 -o - %s | FileCheck %s --check-prefixes=CHECK,OFFSET
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#if !__has_feature(kcfi)
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#error Missing kcfi?
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#endif
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/// Must emit __kcfi_typeid symbols for address-taken function declarations
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// CHECK: module asm ".weak __kcfi_typeid_[[F4:[a-zA-Z0-9_]+]]"
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// CHECK: module asm ".set __kcfi_typeid_[[F4]], [[#%d,HASH:]]"
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/// Must not __kcfi_typeid symbols for non-address-taken declarations
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// CHECK-NOT: module asm ".weak __kcfi_typeid_{{f6|_Z2f6v}}"
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typedef int (*fn_t)(void);
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// CHECK: define dso_local{{.*}} i32 @{{f1|_Z2f1v}}(){{.*}} !kcfi_type ![[#TYPE:]]
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int f1(void) { return 0; }
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// CHECK: define dso_local{{.*}} i32 @{{f2|_Z2f2v}}(){{.*}} !kcfi_type ![[#TYPE2:]]
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unsigned int f2(void) { return 2; }
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// CHECK-LABEL: define dso_local{{.*}} i32 @{{__call|_Z6__callPFivE}}(ptr{{.*}} %f)
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int __call(fn_t f) __attribute__((__no_sanitize__("kcfi"))) {
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// CHECK-NOT: call{{.*}} i32 %{{.}}(){{.*}} [ "kcfi"
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return f();
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}
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// CHECK: define dso_local{{.*}} i32 @{{call|_Z4callPFivE}}(ptr{{.*}} %f){{.*}}
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int call(fn_t f) {
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// CHECK: call{{.*}} i32 %{{.}}(){{.*}} [ "kcfi"(i32 [[#HASH]]) ]
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return f();
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}
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// CHECK-DAG: define internal{{.*}} i32 @{{f3|_ZL2f3v}}(){{.*}} !kcfi_type ![[#TYPE]]
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static int f3(void) { return 1; }
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// CHECK-DAG: declare !kcfi_type ![[#TYPE]]{{.*}} i32 @[[F4]]()
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extern int f4(void);
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/// Must not emit !kcfi_type for non-address-taken local functions
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// CHECK: define internal{{.*}} i32 @{{f5|_ZL2f5v}}()
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// CHECK-NOT: !kcfi_type
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// CHECK-SAME: {
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static int f5(void) { return 2; }
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// CHECK-DAG: declare !kcfi_type ![[#TYPE]]{{.*}} i32 @{{f6|_Z2f6v}}()
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extern int f6(void);
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int test(void) {
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return call(f1) +
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__call((fn_t)f2) +
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call(f3) +
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call(f4) +
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f5() +
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f6();
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}
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// CHECK-DAG: ![[#]] = !{i32 4, !"kcfi", i32 1}
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// OFFSET-DAG: ![[#]] = !{i32 4, !"kcfi-offset", i32 3}
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// CHECK-DAG: ![[#TYPE]] = !{i32 [[#HASH]]}
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// CHECK-DAG: ![[#TYPE2]] = !{i32 [[#%d,HASH2:]]}
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