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BFS: _SplitNode() could overflow the new node.

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* When the keys were large enough, a large key entering the node could
  overflow the available data in the target node. This caused tree and
  memory corruption.
* This fixes bug #6034.
This commit is contained in:
Axel Dörfler
2015-01-19 21:21:12 +01:00
parent f1dd9654ed
commit 8b6e513a2e
1 changed files with 13 additions and 12 deletions
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src/add-ons/kernel/file_systems/bfs/BPlusTree.cpp
+13 -12
View File
@@ -1,5 +1,5 @@
/*
* Copyright 2001-2014, Axel Dörfler, [email protected].
* Copyright 2001-2015, Axel Dörfler, [email protected].
* This file may be used under the terms of the MIT License.
*
* Roughly based on 'btlib' written by Marcus J. Ranum - it shares
@@ -1433,8 +1433,8 @@ BPlusTree::_SplitNode(bplustree_node* node, off_t nodeOffset,
return B_BAD_VALUE;
}
// how many keys will fit in one (half) page?
// that loop will find the answer to this question and
// How many keys will fit in one (half) page?
// The following loop will find the answer to this question and
// change the key lengths indices for their new home
// "bytes" is the number of bytes written for the new key,
@@ -1444,25 +1444,23 @@ BPlusTree::_SplitNode(bplustree_node* node, off_t nodeOffset,
size_t size = fNodeSize >> 1;
int32 out, in;
size_t keyLengths = 0;
for (in = out = 0; in < node->NumKeys() + 1;) {
if (!bytes) {
bytesBefore = in > 0
? BFS_ENDIAN_TO_HOST_INT16(inKeyLengths[in - 1]) : 0;
}
keyLengths = BFS_ENDIAN_TO_HOST_INT16(inKeyLengths[in]);
if (in == keyIndex && !bytes) {
bytes = *_keyLength;
bytesBefore = in > 0
? BFS_ENDIAN_TO_HOST_INT16(inKeyLengths[in - 1]) : 0;
} else {
if (keyIndex < out) {
bytesAfter = BFS_ENDIAN_TO_HOST_INT16(inKeyLengths[in])
- bytesBefore;
}
if (keyIndex < out)
bytesAfter = keyLengths - bytesBefore;
in++;
}
out++;
if (key_align(sizeof(bplustree_node) + bytesBefore + bytesAfter + bytes)
if (key_align(sizeof(bplustree_node) + bytes + keyLengths)
+ out * (sizeof(uint16) + sizeof(off_t)) >= size) {
// we have found the number of keys in the new node!
break;
@@ -1471,8 +1469,11 @@ BPlusTree::_SplitNode(bplustree_node* node, off_t nodeOffset,
// if the new key was not inserted, set the length of the keys
// that can be copied directly
if (keyIndex >= out && in > 0)
bytesBefore = BFS_ENDIAN_TO_HOST_INT16(inKeyLengths[in - 1]);
else if (keyIndex + 1 < out)
bytesAfter = keyLengths - bytesBefore;
if (bytesBefore < 0 || bytesAfter < 0)
return B_BAD_DATA;