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[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
This commit is contained in:
Jianzhou Zhao 2021-01-12 21:49:59 +00:00
parent 25eb7b08ba
commit 82655c1514
1 changed files with 7 additions and 5 deletions
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12
compiler-rt/lib/msan/msan_poisoning.cpp
View File

@ -47,7 +47,7 @@ void CopyOrigin(const void *dst, const void *src, uptr size,
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 @@ void CopyOrigin(const void *dst, const void *src, uptr size,
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 @@ void CopyOrigin(const void *dst, const void *src, uptr size,
*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);
}
}
}