Issue 82 in memory-sanitizer: Origin lost in unaligned memcpy

[memory-s...@googlecode.com]

Status: Accepted
Owner: euge...@google.com
Labels: Type-Defect Priority-Medium

New issue 82 by euge...@google.com: Origin lost in unaligned memcpy
https://code.google.com/p/memory-sanitizer/issues/detail?id=82

Clang r227077.

#include <sanitizer/msan_interface.h>
#include <string.h>

int main() {
char x[8];
char y[8];

memset(x, 0, 8);
__msan_allocated_memory(&x[6], 1);

memset(y, 0, 8);
memcpy(y + 1, x, 7);

__msan_print_shadow(y + 1, 7);
return 0;
}

Compile with -fsanitize=memory -fsanitize-memory-track-origins=2.

Output:

Shadow map of [0x3fffb04da71d, 0x3fffb04da724), 7 bytes:
0x3fffb04da71c: ..000000 000000ff ........ ........ |. A . .|

Origin A (origin_id 80000002):
Uninitialized value was created by an allocation of 'y' in the stack
frame of function 'main'
#0 0x7f2811843410 in main (/code/llvm/build/a.out+0x70410)

memcpy() did not update origin for y.

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