https://github.com/gbMattN updated
https://github.com/llvm/llvm-project/pull/95387
>From 8099113d68bd7c47c29f635bb10a048ddb99833b Mon Sep 17 00:00:00 2001
From: Matthew Nagy <gbm...@tiger-linux2.domain.snsys.com>
Date: Fri, 28 Jun 2024 16:12:31 +0000
Subject: [PATCH 1/2] [TySan] Fixed false positive when accessing global
object's member variables
---
compiler-rt/lib/tysan/tysan.cpp | 19 +++++++++++-
.../test/tysan/global-struct-members.c | 31 +++++++++++++++++++
2 files changed, 49 insertions(+), 1 deletion(-)
create mode 100644 compiler-rt/test/tysan/global-struct-members.c
diff --git a/compiler-rt/lib/tysan/tysan.cpp b/compiler-rt/lib/tysan/tysan.cpp
index f627851d049e6a..8235b0ec2b55e7 100644
--- a/compiler-rt/lib/tysan/tysan.cpp
+++ b/compiler-rt/lib/tysan/tysan.cpp
@@ -221,7 +221,24 @@ __tysan_check(void *addr, int size, tysan_type_descriptor
*td, int flags) {
OldTDPtr -= i;
OldTD = *OldTDPtr;
- if (!isAliasingLegal(td, OldTD))
+ // When shadow memory is set for global objects, the entire object is
tagged with the struct type
+ // This means that when you access a member variable, tysan reads that as
you accessing a struct midway
+ // through, with 'i' being the offset
+ // Therefore, if you are accessing a struct, we need to find the member
type. We can go through the
+ // members of the struct type and see if there is a member at the offset
you are accessing the struct by.
+ // If there is indeed a member starting at offset 'i' in the struct, we
should check aliasing legality
+ // with that type. If there isn't, we run alias checking on the struct
with will give us the correct error.
+ tysan_type_descriptor *InternalMember = OldTD;
+ if (OldTD->Tag == TYSAN_STRUCT_TD) {
+ for (int j = 0; j < OldTD->Struct.MemberCount; j++) {
+ if (OldTD->Struct.Members[j].Offset == i) {
+ InternalMember = OldTD->Struct.Members[j].Type;
+ break;
+ }
+ }
+ }
+
+ if (!isAliasingLegal(td, InternalMember))
reportError(addr, size, td, OldTD, AccessStr,
"accesses part of an existing object", -i, pc, bp, sp);
diff --git a/compiler-rt/test/tysan/global-struct-members.c
b/compiler-rt/test/tysan/global-struct-members.c
new file mode 100644
index 00000000000000..76ea3c431dd7bc
--- /dev/null
+++ b/compiler-rt/test/tysan/global-struct-members.c
@@ -0,0 +1,31 @@
+// RUN: %clang_tysan -O0 %s -o %t && %run %t >%t.out 2>&1
+// RUN: FileCheck %s < %t.out
+
+#include <stdio.h>
+
+struct X {
+ int a, b, c;
+} x;
+
+static struct X xArray[2];
+
+int main() {
+ x.a = 1;
+ x.b = 2;
+ x.c = 3;
+
+ printf("%d %d %d\n", x.a, x.b, x.c);
+ // CHECK-NOT: ERROR: TypeSanitizer: type-aliasing-violation
+
+ for (size_t i = 0; i < 2; i++) {
+ xArray[i].a = 1;
+ xArray[i].b = 1;
+ xArray[i].c = 1;
+ }
+
+ struct X *xPtr = (struct X *)&(xArray[0].c);
+ xPtr->a = 1;
+ // CHECK: ERROR: TypeSanitizer: type-aliasing-violation
+ // CHECK: WRITE of size 4 at {{.*}} with type int (in X at offset 0)
accesses an existing object of type int (in X at offset 8)
+ // CHECK: {{#0 0x.* in main .*struct-members.c:}}[[@LINE-3]]
+}
>From 83a368867533e316b4272c19d0bf61da842c5b4b Mon Sep 17 00:00:00 2001
From: Matthew Nagy <gbm...@tiger-linux2.domain.snsys.com>
Date: Thu, 12 Sep 2024 10:52:19 +0000
Subject: [PATCH 2/2] Fix more member offset bugs
---
compiler-rt/lib/tysan/tysan.cpp | 25 +++++++++------
.../tysan/struct-offset-different-base.cpp | 31 +++++++++++++++++++
2 files changed, 47 insertions(+), 9 deletions(-)
create mode 100644 compiler-rt/test/tysan/struct-offset-different-base.cpp
diff --git a/compiler-rt/lib/tysan/tysan.cpp b/compiler-rt/lib/tysan/tysan.cpp
index 8235b0ec2b55e7..abad429de7ed9b 100644
--- a/compiler-rt/lib/tysan/tysan.cpp
+++ b/compiler-rt/lib/tysan/tysan.cpp
@@ -128,8 +128,13 @@ static bool isAliasingLegalUp(tysan_type_descriptor *TDA,
break;
}
- OffsetA -= TDA->Struct.Members[Idx].Offset;
- TDA = TDA->Struct.Members[Idx].Type;
+ if (TDA->Struct.Members[Idx].Offset > OffsetA) {
+ OffsetA = TDA->Struct.Members[Idx].Offset - OffsetA;
+ TDA = TDA->Struct.Members[Idx - 1].Type;
+ } else {
+ OffsetA -= TDA->Struct.Members[Idx].Offset;
+ TDA = TDA->Struct.Members[Idx].Type;
+ }
} else {
DCHECK(0);
break;
@@ -221,13 +226,15 @@ __tysan_check(void *addr, int size, tysan_type_descriptor
*td, int flags) {
OldTDPtr -= i;
OldTD = *OldTDPtr;
- // When shadow memory is set for global objects, the entire object is
tagged with the struct type
- // This means that when you access a member variable, tysan reads that as
you accessing a struct midway
- // through, with 'i' being the offset
- // Therefore, if you are accessing a struct, we need to find the member
type. We can go through the
- // members of the struct type and see if there is a member at the offset
you are accessing the struct by.
- // If there is indeed a member starting at offset 'i' in the struct, we
should check aliasing legality
- // with that type. If there isn't, we run alias checking on the struct
with will give us the correct error.
+ // When shadow memory is set for global objects, the entire object is
tagged
+ // with the struct type This means that when you access a member variable,
+ // tysan reads that as you accessing a struct midway through, with 'i'
being
+ // the offset Therefore, if you are accessing a struct, we need to find the
+ // member type. We can go through the members of the struct type and see if
+ // there is a member at the offset you are accessing the struct by. If
there
+ // is indeed a member starting at offset 'i' in the struct, we should check
+ // aliasing legality with that type. If there isn't, we run alias checking
+ // on the struct with will give us the correct error.
tysan_type_descriptor *InternalMember = OldTD;
if (OldTD->Tag == TYSAN_STRUCT_TD) {
for (int j = 0; j < OldTD->Struct.MemberCount; j++) {
diff --git a/compiler-rt/test/tysan/struct-offset-different-base.cpp
b/compiler-rt/test/tysan/struct-offset-different-base.cpp
new file mode 100644
index 00000000000000..c2986522198ab4
--- /dev/null
+++ b/compiler-rt/test/tysan/struct-offset-different-base.cpp
@@ -0,0 +1,31 @@
+// RUN: %clangxx_tysan -O0 %s -c -o %t.o
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+
+struct inner {
+ char buffer;
+ int i;
+};
+
+void init_inner(inner *list) {
+ list->i = 0;
+}
+
+struct outer {
+ inner foo;
+ char buffer;
+};
+
+int main(void) {
+ outer *l = new outer();
+
+ init_inner(&l->foo);
+
+ int access_offsets_with_different_base = l->foo.i;
+ printf("%d\n", access_offsets_with_different_base);
+
+ return 0;
+}
+
+// CHECK-NOT: ERROR: TypeSanitizer: type-aliasing-violation
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