Hello,
With the experts' help in this community, I've enabled the Asan for global
and stack buffer in my bare-mental platform firmware, thanks a lot.
But I find the current Asan doesn't support to protect the structure inner
elements, E.g. the global_array[11] in below code. Unfortunately, most of
important data are defined through structure in my firmware, and if the
Asan doesn't support to protect structure inner elements, most of my data
memory access will not be protected by Asan. So, could we let Asan support
structure inner elements?
Well, I understand it is not safe to just instrument red-zone between
structure inner elements like current Asan does on global variable. We
also need to handle the sizeof(), offsetof() macro, the alignment pragma,
and maybe others. Could we extend Asan scope beyond IR to Clang front-end
to do some source-to-source conversion to handle these issue? E.g. for no
alignment enforced structure, replace the structure inner elements with
red-zone instrumented version, and let the sizeof() be-aware of the size
change. Is it possible?
#include <stdio.h>
#pragma pack (1)
typedef struct {
int Name;
int Version;
} HEADER;
#pragma pack ()
typedef struct {
HEADER Header;
int global_array[11];
int Tailer;
} TABLE;
TABLE Table;
int main(int argc, char **argv) {
int Num;
void *ptr;
Num = 11;
Table.global_array[Num] = 0x87654321; // redzones is only rounded up to
bound of the structure outermost which cause miss structure inner field
buffer overflow here
printf("Table.global_array[%d]=0x%x\n", Num, Table.global_array[Num]);
Table.global_array[0] = 0x12345678;
ptr = &Table;
ptr += sizeof(Table.Header); // Could we let the "sizeof" be Asan aware
to support RedZone instrumentation in structure inner field?
printf("*ptr=0x%x\n", *(unsigned int *)ptr);
return 1;
}
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