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Reland "[scudo] Apply filling when realloc shrinks and re-grows a block in-place" (#95838)

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Reland of #93212, which had been reverted in
commit bddd8eae17df6511aee789744ccdc158de817081.
This commit is contained in:
Fabio D'Urso 2024-06-19 09:37:23 +02:00 committed by GitHub
parent 519175c3f5
commit 7fc975aa26
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GPG Key ID: B5690EEEBB952194
2 changed files with 31 additions and 5 deletions
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13
compiler-rt/lib/scudo/standalone/combined.h
View File

@ -549,6 +549,19 @@ public:
// header to reflect the size change.
if (reinterpret_cast<uptr>(OldTaggedPtr) + NewSize <= BlockEnd) {
if (NewSize > OldSize || (OldSize - NewSize) < getPageSizeCached()) {
// If we have reduced the size, set the extra bytes to the fill value
// so that we are ready to grow it again in the future.
if (NewSize < OldSize) {
const FillContentsMode FillContents =
TSDRegistry.getDisableMemInit() ? NoFill
: Options.getFillContentsMode();
if (FillContents != NoFill) {
memset(reinterpret_cast<char *>(OldTaggedPtr) + NewSize,
FillContents == ZeroFill ? 0 : PatternFillByte,
OldSize - NewSize);
}
}
Header.SizeOrUnusedBytes =
(ClassId ? NewSize
: BlockEnd -

23
compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
View File

@ -447,19 +447,32 @@ SCUDO_TYPED_TEST(ScudoCombinedDeathTest, ReallocateSame) {
// returns the same chunk. This requires that all the sizes we iterate on use
// the same block size, but that should be the case for MaxSize - 64 with our
// default class size maps.
constexpr scudo::uptr ReallocSize =
constexpr scudo::uptr InitialSize =
TypeParam::Primary::SizeClassMap::MaxSize - 64;
void *P = Allocator->allocate(ReallocSize, Origin);
const char Marker = 'A';
memset(P, Marker, ReallocSize);
Allocator->setFillContents(scudo::PatternOrZeroFill);
void *P = Allocator->allocate(InitialSize, Origin);
scudo::uptr CurrentSize = InitialSize;
for (scudo::sptr Delta = -32; Delta < 32; Delta += 8) {
memset(P, Marker, CurrentSize);
const scudo::uptr NewSize =
static_cast<scudo::uptr>(static_cast<scudo::sptr>(ReallocSize) + Delta);
static_cast<scudo::uptr>(static_cast<scudo::sptr>(InitialSize) + Delta);
void *NewP = Allocator->reallocate(P, NewSize);
EXPECT_EQ(NewP, P);
for (scudo::uptr I = 0; I < ReallocSize - 32; I++)
// Verify that existing contents have been preserved.
for (scudo::uptr I = 0; I < scudo::Min(CurrentSize, NewSize); I++)
EXPECT_EQ((reinterpret_cast<char *>(NewP))[I], Marker);
// Verify that new bytes are set according to FillContentsMode.
for (scudo::uptr I = CurrentSize; I < NewSize; I++) {
unsigned char V = (reinterpret_cast<unsigned char *>(NewP))[I];
EXPECT_TRUE(V == scudo::PatternFillByte || V == 0);
}
checkMemoryTaggingMaybe(Allocator, NewP, NewSize, 0);
CurrentSize = NewSize;
}
Allocator->deallocate(P, Origin);
}