https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66308
Bug ID: 66308
Summary: -fsanitize=alignment is missing "downcast of
misaligned address" checks
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org
Target Milestone: ---
GCC doesn't give any runtime error for this testcase:
struct node_base {
char c;
};
struct node : node_base {
long long l;
};
int main()
{
unsigned char buf[sizeof(node_base)+1];
node_base* n = (node_base*)(buf+1);
(void) static_cast<node*>(n);
}
Clang says:
uba.cc:13:10: runtime error: downcast of misaligned address 0x7ffdd521f2eb for
type 'node', which requires 8 byte alignment
0x7ffdd521f2eb: note: pointer points here
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 65 1d e2 36 32 00 00 00
00 00 00 00 00 00 00
^
