7f93ae8086
The -fstrict-flex-arrays=3 is the most restrictive type of flex arrays.
No number, including 0, is allowed in the FAM. In the cases where a "0"
is used, the resulting size is the same as if a zero-sized object were
substituted.
This is needed for proper _FORTIFY_SOURCE coverage in the Linux kernel,
among other reasons. So while the only reason for specifying a
zero-length array at the end of a structure is for specify a FAM,
treating it as such will cause _FORTIFY_SOURCE not to work correctly;
__builtin_object_size will report -1 instead of 0 for a destination
buffer size to keep any kernel internals from using the deprecated
members as fake FAMs.
For example:
struct broken {
int foo;
int fake_fam[0];
struct something oops;
};
There have been bugs where the above struct was created because "oops"
was added after "fake_fam" by someone not realizing. Under
__FORTIFY_SOURCE, doing:
memcpy(p->fake_fam, src, len);
raises no warnings when __builtin_object_size(p->fake_fam, 1) returns -1
and may stomp on "oops."
Omitting a warning when using the (invalid) zero-length array is how GCC
treats -fstrict-flex-arrays=3. A warning in that situation is likely an
irritant, because requesting this option level is explicitly requesting
this behavior.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
Differential Revision: https://reviews.llvm.org/D134902
169 lines
5.7 KiB
C
169 lines
5.7 KiB
C
// REQUIRES: x86-registered-target
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=0 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-0
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=0 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-0,CXX,CXX-STRICT-0
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=1 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-1
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=1 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-1,CXX
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=2 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-2
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=2 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-2,CXX
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=3 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-3
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// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=3 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-3,CXX
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// Before flexible array member was added to C99, many projects use a
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// one-element array as the last member of a structure as an alternative.
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// E.g. https://github.com/python/cpython/issues/84301
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// Suppress such errors with -fstrict-flex-arrays=0.
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struct Incomplete {
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int ignored;
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int a[];
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};
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struct Zero {
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int ignored;
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int a[0];
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};
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struct One {
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int ignored;
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int a[1];
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};
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struct Two {
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int ignored;
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int a[2];
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};
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struct Three {
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int ignored;
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int a[3];
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};
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// CHECK-LABEL: define {{.*}} @{{.*}}test_incomplete{{.*}}(
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int test_incomplete(struct Incomplete *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1-NOT: @__ubsan
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// CHECK-STRICT-2-NOT: @__ubsan
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// CHECK-STRICT-3-NOT: @__ubsan
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_zero{{.*}}(
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int test_zero(struct Zero *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1-NOT: @__ubsan
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// CHECK-STRICT-2-NOT: @__ubsan
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_one{{.*}}(
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int test_one(struct One *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1-NOT: @__ubsan
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_two{{.*}}(
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int test_two(struct Two *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_three{{.*}}(
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int test_three(struct Three *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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union uZero {
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int a[0];
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};
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union uOne {
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int a[1];
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};
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union uTwo {
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int a[2];
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};
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union uThree {
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int a[3];
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};
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// CHECK-LABEL: define {{.*}} @{{.*}}test_uzero{{.*}}(
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int test_uzero(union uZero *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1-NOT: @__ubsan
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// CHECK-STRICT-2-NOT: @__ubsan
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_uone{{.*}}(
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int test_uone(union uOne *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1-NOT: @__ubsan
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_utwo{{.*}}(
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int test_utwo(union uTwo *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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// CHECK-LABEL: define {{.*}} @{{.*}}test_uthree{{.*}}(
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int test_uthree(union uThree *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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#define FLEXIBLE 1
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struct Macro {
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int a[FLEXIBLE];
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};
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// CHECK-LABEL: define {{.*}} @{{.*}}test_macro{{.*}}(
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int test_macro(struct Macro *p, int i) {
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// CHECK-STRICT-0-NOT: @__ubsan
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// CHECK-STRICT-1-NOT: @__ubsan
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// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
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// CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
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return p->a[i] + (p->a)[i];
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}
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#if defined __cplusplus
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struct Base {
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int b;
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};
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struct NoStandardLayout : Base {
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int a[1];
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};
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// CXX-LABEL: define {{.*}} @{{.*}}test_nostandardlayout{{.*}}(
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int test_nostandardlayout(NoStandardLayout *p, int i) {
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// CXX-STRICT-0-NOT: @__ubsan
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return p->a[i] + (p->a)[i];
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}
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template<int N> struct Template {
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int a[N];
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};
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// CXX-LABEL: define {{.*}} @{{.*}}test_template{{.*}}(
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int test_template(Template<1> *p, int i) {
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// CXX-STRICT-0-NOT: @__ubsan
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return p->a[i] + (p->a)[i];
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}
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#endif
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