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[scudo] Apply filling option when realloc grows a block in-place too #93212

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Merged
merged 3 commits into from
Jun 10, 2024
Merged

[scudo] Apply filling option when realloc grows a block in-place too #93212

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1e55c81
[scudo] Apply filling option when realloc grows a block in-place too
fabio-d May 23, 2024
17625ca
Moved test to ScudoCombinedDeathTest::ReallocateSame
fabio-d Jun 4, 2024
4826711
Apply fill when shrank instead of when grown
fabio-d Jun 5, 2024
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14 changes: 14 additions & 0 deletions compiler-rt/lib/scudo/standalone/combined.h
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Original file line number Diff line number Diff line change
Expand Up @@ -565,6 +565,20 @@ class Allocator {
storeSecondaryAllocationStackMaybe(Options, OldPtr, NewSize);
}
}

// 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);
}
}

return OldTaggedPtr;
}
}
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23 changes: 18 additions & 5 deletions compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
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Expand Up @@ -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++) {
EXPECT_EQ((reinterpret_cast<unsigned char *>(NewP))[I],
scudo::PatternFillByte);
}

Comment on lines +468 to +473
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I guess we only want to include this when it doesn't have GWP_ASAN_HOOKS defined.

checkMemoryTaggingMaybe(Allocator, NewP, NewSize, 0);
CurrentSize = NewSize;
}
Allocator->deallocate(P, Origin);
}
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