[MSan] Tweak CopyOrigin
There could be some mis-alignments when copying origins not aligned.
I believe inaligned memcpy is rare so the cases do not matter too much
in practice.
1) About the change at line 50
Let dst be (void*)5,
then d=5, beg=4
so we need to write 3 (4+4-5) bytes from 5 to 7.
2) About the change around line 77.
Let dst be (void*)5,
because of lines 50-55, the bytes from 5-7 were already writen.
So the aligned copy is from 8.
Reviewed-by: eugenis
Differential Revision: https://reviews.llvm.org/D94552
GitOrigin-RevId: 82655c151450e0103a3aa60725639da607f9220c
diff --git a/lib/msan/msan_poisoning.cpp b/lib/msan/msan_poisoning.cpp
index ef3c74e..8f58432 100644
--- a/lib/msan/msan_poisoning.cpp
+++ b/lib/msan/msan_poisoning.cpp
@@ -47,7 +47,7 @@
uptr beg = d & ~3UL;
// Copy left unaligned origin if that memory is poisoned.
if (beg < d) {
- u32 o = GetOriginIfPoisoned((uptr)src, d - beg);
+ u32 o = GetOriginIfPoisoned((uptr)src, beg + 4 - d);
if (o) {
if (__msan_get_track_origins() > 1) o = ChainOrigin(o, stack);
*(u32 *)MEM_TO_ORIGIN(beg) = o;
@@ -71,12 +71,13 @@
if (beg < end) {
// Align src up.
uptr s = ((uptr)src + 3) & ~3UL;
+ uptr aligned_beg = ((uptr)dst + 3) & ~3UL;
// FIXME: factor out to msan_copy_origin_aligned
if (__msan_get_track_origins() > 1) {
u32 *src = (u32 *)MEM_TO_ORIGIN(s);
u32 *src_s = (u32 *)MEM_TO_SHADOW(s);
- u32 *src_end = (u32 *)MEM_TO_ORIGIN(s + (end - beg));
- u32 *dst = (u32 *)MEM_TO_ORIGIN(beg);
+ u32 *src_end = (u32 *)MEM_TO_ORIGIN(s + (end - aligned_beg));
+ u32 *dst = (u32 *)MEM_TO_ORIGIN(aligned_beg);
u32 src_o = 0;
u32 dst_o = 0;
for (; src < src_end; ++src, ++src_s, ++dst) {
@@ -88,8 +89,9 @@
*dst = dst_o;
}
} else {
- REAL(memcpy)((void *)MEM_TO_ORIGIN(beg), (void *)MEM_TO_ORIGIN(s),
- end - beg);
+ REAL(memcpy)
+ ((void *)MEM_TO_ORIGIN(aligned_beg), (void *)MEM_TO_ORIGIN(s),
+ end - aligned_beg);
}
}
}