| Issue |
146579
|
| Summary |
[[clang::unsafe_buffer_usage]] Source range in unsafe pointer arithmetic warning doesn't show entire unsafe operation
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
tsepez
|
Given a file range0.cc:
```
int lookup(int *ptr, unsigned idx) {
return ptr[idx];
}
int* predecrement(int* ptr) {
return --ptr; // not actually useful, only for example
}
```
```
range0.cc:3:10:{3:10-3:13}: warning: unsafe buffer access [-Wunsafe-buffer-usage]
3 | return ptr[idx];
| ^~~
range0.cc:3:10: note: pass -fsafe-buffer-usage-suggestions to receive code hardening suggestions
range0.cc:7:12:{7:12-7:15}: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage]
7 | return --ptr; // not actually useful, only for example
| ^~~
```
The returned range indicates only the unsafe operand rather than the range of the unsafe operation.
We seek to automate applying the _Pragma("clang unsafe_buffer_usage begin") / _Pragma("clang unsafe_buffer_usage end") form of suppression around the ranges as exactly indicated by the compiler,
and using some macro trickery, i.e.
```
#define UNSAFE_BUFFERS(...) \
_Pragma("clang unsafe_buffer_usage begin") \
__VA_ARGS__ \
_Pragma("clang unsafe_buffer_usage end")
int lookup(int *ptr, unsigned idx) {
return UNSAFE_BUFFERS(ptr)[idx];
}
int* predecrement2(int* ptr) {
return --UNSAFE_BUFFERS(ptr); // not actually useful, only for example
}
```
The ptr[idx] looks unusual but does suppress the error. The --ptr case, however gives
```
range1.cc:12:27: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage]
12 | return --UNSAFE_BUFFERS(ptr); // not actually useful, only for example
| ^~~
```
The returned range should cover the entire unsafe operation, not the unsafe argument allowing us to write
```
int lookup(int *ptr, unsigned idx) {
return UNSAFE_BUFFERS(ptr[idx]);
}
int* predecrement(int* ptr) {
return UNSAFE_BUFFERS(--ptr); // not actually useful, only for example
}
```
which compiles cleanly
![]()
_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
