ndimiduk commented on a change in pull request #2380:
URL: https://github.com/apache/hbase/pull/2380#discussion_r486642223
##########
File path:
hbase-common/src/main/java/org/apache/hadoop/hbase/util/UnsafeAccess.java
##########
@@ -327,6 +327,11 @@ public static void copy(byte[] src, int srcOffset,
ByteBuffer dest, int destOffs
destBase = dest.array();
}
long srcAddress = srcOffset + BYTE_ARRAY_BASE_OFFSET;
+ assert (src.length - srcOffset) >= length : "unsafe memory access:
attempting to copy "
+ + length + " bytes from src when only " + (src.length - srcOffset) + "
capacity remains";
+ assert (dest.capacity() - destOffset) >= length : "unsafe memory access:
attempting to copy "
+ + length + " bytes into dest when only " + (dest.capacity() - destOffset)
+ + " capacity remains.";
unsafeCopy(src, srcAddress, destBase, destAddress, length);
Review comment:
These `assert` are protecting calls to the method invoked by
`unsafeCopy`: `Unsafe.copyMemory`. The documentation on that method makes no
mention of bounds checking, and indeed I don't think it can because it accepts
`Object,long` as parameters describing the source and destination memory
addresses.
From AdoptOpenJDK:
```
/**
* Sets all bytes in a given block of memory to a copy of another
* block.
*
* <p>This method determines each block's base address by means of two
parameters,
* and so it provides (in effect) a <em>double-register</em> addressing
mode,
* as discussed in {@link #getInt(Object,long)}. When the object
reference is null,
* the offset supplies an absolute base address.
*
* <p>The transfers are in coherent (atomic) units of a size determined
* by the address and length parameters. If the effective addresses and
* length are all even modulo 8, the transfer takes place in 'long'
units.
* If the effective addresses and length are (resp.) even modulo 4 or 2,
* the transfer takes place in units of 'int' or 'short'.
*
* @since 1.7
*/
public native void copyMemory(Object srcBase, long srcOffset,
Object destBase, long destOffset,
long bytes);
```
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