Tree normailization tries to reshape expr tree into a normal from like
|1 |1
/ \ / \
|2 T -> a |2
/ \ / \
|3 c b |3
/ \ / \
a b c T
which requires rotating the alt and cat nodes, at the same time it
also tries to rotate epsnods to the same side as alt and cat nodes.
However there is a bug that results in the epsnode flipping and
node rotation reverting each others work. If the tree is of the
follow form this will result in an infinite loop.
|1
/ \
e2 |3
/ \
e3 C
epsnode flipping is not supposed to take precedence over node rotation
and there is even a test to check for an alt or cat node, unfortunately
it is wrong resulting in unnecessary swapping and the possibility for
the above infinite loop
Signed-off-by: John Johansen <[email protected]>
---
parser/libapparmor_re/expr-tree.cc | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/parser/libapparmor_re/expr-tree.cc
b/parser/libapparmor_re/expr-tree.cc
index e9a1275..b502d54 100644
--- a/parser/libapparmor_re/expr-tree.cc
+++ b/parser/libapparmor_re/expr-tree.cc
@@ -189,7 +189,7 @@ void normalize_tree(Node *t, int dir)
for (;;) {
if ((&epsnode == t->child[dir]) &&
(&epsnode != t->child[!dir]) &&
- dynamic_cast<TwoChildNode *>(t)) {
+ !dynamic_cast<TwoChildNode *>(t->child[!dir])) {
// (E | a) -> (a | E)
// Ea -> aE
Node *c = t->child[dir];
--
1.7.9
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