From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: linux-sparse@vger.kernel.org
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: [PATCH] fix eval of the assignment of a non-restricted value to a restricted variable
Date: Thu, 25 Feb 2021 23:05:37 +0100 [thread overview]
Message-ID: <20210225220537.95335-1-luc.vanoostenryck@gmail.com> (raw)
Assignment to restricted variables are severely ... restricted.
Nevertheless, one value is always fine because it has always
the same bit representation: 0.
So, 0 is accepted unconditionally but this creates a problem
because the type of this 0 needs to be adjusted. Otherwise
0 (int) is assigned as-is even on restricted variable with a
different bit-length.
Fix this by casting the value to the target type before accepting it.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
evaluate.c | 2 +-
validation/eval/assign-restricted-ok.c | 22 ++++++++++++++++++++++
2 files changed, 23 insertions(+), 1 deletion(-)
create mode 100644 validation/eval/assign-restricted-ok.c
diff --git a/evaluate.c b/evaluate.c
index 41871e18503a..a661027f8df6 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -1442,7 +1442,7 @@ static int check_assignment_types(struct symbol *target, struct expression **rp,
if (sclass & TYPE_FOULED && unfoul(s) == t)
goto Cast;
if (!restricted_value(*rp, target))
- return 1;
+ goto Cast;
if (s == t)
return 1;
} else if (!(sclass & TYPE_RESTRICT))
diff --git a/validation/eval/assign-restricted-ok.c b/validation/eval/assign-restricted-ok.c
new file mode 100644
index 000000000000..df94d8c9d6d0
--- /dev/null
+++ b/validation/eval/assign-restricted-ok.c
@@ -0,0 +1,22 @@
+#ifdef __CHECKER__
+#define __bitwise __attribute__((bitwise))
+#else
+#define __bitwise
+#endif
+
+typedef __INT16_TYPE__ __bitwise __be16;
+
+static __be16 foo(void)
+{
+ __be16 val = 0;
+ return val;
+}
+
+/*
+ * check-name: assign-restricted-ok
+ * check-command: test-linearize -fdump-ir $file
+ *
+ * check-output-ignore
+ * check-output-contains: store\\.16
+ * check-output-excludes: store\\.32
+ */
--
2.30.0
reply other threads:[~2021-02-25 22:06 UTC|newest]
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