https://github.com/DonatNagyE updated
https://github.com/llvm/llvm-project/pull/66109:
>From b5c45907b0a5c075dfdbd7f6b3727634d976787b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Don=C3=A1t=20Nagy?= <donat.n...@ericsson.com>
Date: Tue, 12 Sep 2023 18:07:34 +0200
Subject: [PATCH] [analyzer] Fix StdLibraryFunctionsChecker crash on surprising
sink node
Recent changes in StdLibraryFunctionsChecker introduced a situation
where the checker sequentially performed two state transitions to add
two separate note tags.
In the unlikely case when the updated state (the variable `NewState`)
was posteriorly overconstrained, the engine marked the node after the
first state transition as a sink to stop the "natural" graph exploration
after that point.
However, in this particular case the checker tried to directly add a
second node, and this triggered an assertion in the `addPredecessor()`
method of `ExplodedNode`.
This commit introduces an explicit `isSink()` check to avoid this crash.
To avoid similar bugs in the future, perhaps it would be possible to
tweak `addTransition()` and ensure that it returns `nullptr` when it
would return a sink node (to unify the two possible error conditions).
This crash was observed in an analysis of the curl project (in a very
long and complex function), and there I validated that this is the root
cause, but I don't have a self-contained testcase that can trigger the
creation of a PosteriorlyOverconstrained node in this situation.
---
.../Checkers/StdLibraryFunctionsChecker.cpp | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index f5f6e3a91237686..13bb9cef5e490ed 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -1387,8 +1387,8 @@ void StdLibraryFunctionsChecker::checkPostCall(const
CallEvent &Call,
if (!NewState)
continue;
- // It is possible that NewState == State is true.
- // It can occur if another checker has applied the state before us.
+ // Here it's possible that NewState == State, e.g. when other checkers
+ // already applied the same constraints (or stricter ones).
// Still add these note tags, the other checker should add only its
// specialized note tags. These general note tags are handled always by
// StdLibraryFunctionsChecker.
@@ -1427,7 +1427,12 @@ void StdLibraryFunctionsChecker::checkPostCall(const
CallEvent &Call,
});
Pred = C.addTransition(NewState, Pred, Tag);
}
- if (!Pred)
+
+ // Pred may be:
+ // - a nullpointer, if we reach an already existing node
(theoretically);
+ // - a sink, when NewState is posteriorly overconstrained.
+ // In these situations we cannot add the errno note tag.
+ if (!Pred || Pred->isSink())
continue;
}
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