[compiler-rt] Reland "[scudo] Apply filling when realloc shrinks and re-grows a block in-place" (PR #95838)
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Mon Jun 17 13:13:44 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-compiler-rt-sanitizer
Author: Fabio D'Urso (fabio-d)
<details>
<summary>Changes</summary>
Reland of #<!-- -->93212, which has been reverted in
commit bddd8eae17df6511aee789744ccdc158de817081.
---
Full diff: https://github.com/llvm/llvm-project/pull/95838.diff
2 Files Affected:
- (modified) compiler-rt/lib/scudo/standalone/combined.h (+14)
- (modified) compiler-rt/lib/scudo/standalone/tests/combined_test.cpp (+18-5)
``````````diff
diff --git a/compiler-rt/lib/scudo/standalone/combined.h b/compiler-rt/lib/scudo/standalone/combined.h
index f9ed36581f8d3..73da686287747 100644
--- a/compiler-rt/lib/scudo/standalone/combined.h
+++ b/compiler-rt/lib/scudo/standalone/combined.h
@@ -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;
}
}
diff --git a/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp b/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
index 1a36155bcd423..655dc87cbac64 100644
--- a/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
+++ b/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
@@ -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);
+ }
+
checkMemoryTaggingMaybe(Allocator, NewP, NewSize, 0);
+ CurrentSize = NewSize;
}
Allocator->deallocate(P, Origin);
}
``````````
</details>
https://github.com/llvm/llvm-project/pull/95838
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