[clang] [clang][analyzer] Move PutenvStackArrayChecker out of alpha package. (PR #93980)
Balázs Kéri via cfe-commits
cfe-commits at lists.llvm.org
Mon Jun 3 00:55:05 PDT 2024
https://github.com/balazske updated https://github.com/llvm/llvm-project/pull/93980
>From 033c7c2187f4dcbd050c69c5279ae2dcfe02c529 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bal=C3=A1zs=20K=C3=A9ri?= <balazs.keri at ericsson.com>
Date: Wed, 29 May 2024 16:47:42 +0200
Subject: [PATCH 1/2] [clang][analyzer] Move PutenvStackArrayChecker out of
alpha package.
Checker alpha.security.PutenvStackArray is moved to security.PutenvStackArray.
---
clang/docs/analyzer/checkers.rst | 70 +++++++++----------
.../clang/StaticAnalyzer/Checkers/Checkers.td | 10 +--
clang/test/Analysis/putenv-stack-array.c | 2 +-
3 files changed, 41 insertions(+), 41 deletions(-)
diff --git a/clang/docs/analyzer/checkers.rst b/clang/docs/analyzer/checkers.rst
index 3a31708a1e9de..ac13f731e508e 100644
--- a/clang/docs/analyzer/checkers.rst
+++ b/clang/docs/analyzer/checkers.rst
@@ -1179,6 +1179,41 @@ security.insecureAPI.DeprecatedOrUnsafeBufferHandling (C)
strncpy(buf, "a", 1); // warn
}
+.. _security-putenv-stack-array:
+
+security.PutenvStackArray (C)
+"""""""""""""""""""""""""""""
+Finds calls to the ``putenv`` function which pass a pointer to a stack-allocated
+(automatic) array as the argument. Function ``putenv`` does not copy the passed
+string, only a pointer to the data is stored and this data can be read even by
+other threads. Content of a stack-allocated array is likely to be overwritten
+after returning from the parent function.
+
+The problem can be solved by using a static array variable or dynamically
+allocated memory. Even better is to avoid using ``putenv`` (it has other
+problems related to memory leaks) and use ``setenv`` instead.
+
+The check corresponds to CERT rule
+`POS34-C. Do not call putenv() with a pointer to an automatic variable as the argument
+<https://wiki.sei.cmu.edu/confluence/display/c/POS34-C.+Do+not+call+putenv%28%29+with+a+pointer+to+an+automatic+variable+as+the+argument>`_.
+
+.. code-block:: c
+
+ int f() {
+ char env[] = "NAME=value";
+ return putenv(env); // putenv function should not be called with stack-allocated string
+ }
+
+There is one case where the checker can report a false positive. This is when
+the stack-allocated array is used at `putenv` in a function or code branch that
+does not return (calls `fork` or `exec` like function).
+
+Another special case is if the `putenv` is called from function `main`. Here
+the stack is deallocated at the end of the program and it should be no problem
+to use the stack-allocated string (a multi-threaded program may require more
+attention). The checker does not warn for cases when stack space of `main` is
+used at the `putenv` call.
+
security.SetgidSetuidOrder (C)
""""""""""""""""""""""""""""""
When dropping user-level and group-level privileges in a program by using
@@ -2833,41 +2868,6 @@ Warn on mmap() calls that are both writable and executable.
// code
}
-.. _alpha-security-putenv-stack-array:
-
-alpha.security.PutenvStackArray (C)
-"""""""""""""""""""""""""""""""""""
-Finds calls to the ``putenv`` function which pass a pointer to a stack-allocated
-(automatic) array as the argument. Function ``putenv`` does not copy the passed
-string, only a pointer to the data is stored and this data can be read even by
-other threads. Content of a stack-allocated array is likely to be overwritten
-after returning from the parent function.
-
-The problem can be solved by using a static array variable or dynamically
-allocated memory. Even better is to avoid using ``putenv`` (it has other
-problems related to memory leaks) and use ``setenv`` instead.
-
-The check corresponds to CERT rule
-`POS34-C. Do not call putenv() with a pointer to an automatic variable as the argument
-<https://wiki.sei.cmu.edu/confluence/display/c/POS34-C.+Do+not+call+putenv%28%29+with+a+pointer+to+an+automatic+variable+as+the+argument>`_.
-
-.. code-block:: c
-
- int f() {
- char env[] = "NAME=value";
- return putenv(env); // putenv function should not be called with stack-allocated string
- }
-
-There is one case where the checker can report a false positive. This is when
-the stack-allocated array is used at `putenv` in a function or code branch that
-does not return (calls `fork` or `exec` like function).
-
-Another special case is if the `putenv` is called from function `main`. Here
-the stack is deallocated at the end of the program and it should be no problem
-to use the stack-allocated string (a multi-threaded program may require more
-attention). The checker does not warn for cases when stack space of `main` is
-used at the `putenv` call.
-
.. _alpha-security-ReturnPtrRange:
alpha.security.ReturnPtrRange (C)
diff --git a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
index 40f443047bd4b..9ab8e42f7cdcd 100644
--- a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -1011,6 +1011,11 @@ def FloatLoopCounter : Checker<"FloatLoopCounter">,
Dependencies<[SecuritySyntaxChecker]>,
Documentation<HasDocumentation>;
+def PutenvStackArray : Checker<"PutenvStackArray">,
+ HelpText<"Finds calls to the function 'putenv' which pass a pointer to "
+ "an automatic (stack-allocated) array as the argument.">,
+ Documentation<HasDocumentation>;
+
def SetgidSetuidOrderChecker : Checker<"SetgidSetuidOrder">,
HelpText<"Warn on possible reversed order of 'setgid(getgid()))' and "
"'setuid(getuid())' (CERT: POS36-C)">,
@@ -1065,11 +1070,6 @@ def MmapWriteExecChecker : Checker<"MmapWriteExec">,
]>,
Documentation<HasDocumentation>;
-def PutenvStackArray : Checker<"PutenvStackArray">,
- HelpText<"Finds calls to the function 'putenv' which pass a pointer to "
- "an automatic (stack-allocated) array as the argument.">,
- Documentation<HasDocumentation>;
-
def ReturnPointerRangeChecker : Checker<"ReturnPtrRange">,
HelpText<"Check for an out-of-bound pointer being returned to callers">,
Documentation<HasDocumentation>;
diff --git a/clang/test/Analysis/putenv-stack-array.c b/clang/test/Analysis/putenv-stack-array.c
index f28aed73031d3..2099ef4160f85 100644
--- a/clang/test/Analysis/putenv-stack-array.c
+++ b/clang/test/Analysis/putenv-stack-array.c
@@ -1,5 +1,5 @@
// RUN: %clang_analyze_cc1 \
-// RUN: -analyzer-checker=alpha.security.PutenvStackArray \
+// RUN: -analyzer-checker=security.PutenvStackArray \
// RUN: -verify %s
#include "Inputs/system-header-simulator.h"
>From fa0c93d01c73afa9a46004fd99c31e3701adf9ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bal=C3=A1zs=20K=C3=A9ri?= <balazs.keri at ericsson.com>
Date: Mon, 3 Jun 2024 09:54:35 +0200
Subject: [PATCH 2/2] documentation updates
---
clang/docs/analyzer/checkers.rst | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/clang/docs/analyzer/checkers.rst b/clang/docs/analyzer/checkers.rst
index ac13f731e508e..0f237e4a520a9 100644
--- a/clang/docs/analyzer/checkers.rst
+++ b/clang/docs/analyzer/checkers.rst
@@ -1187,7 +1187,7 @@ Finds calls to the ``putenv`` function which pass a pointer to a stack-allocated
(automatic) array as the argument. Function ``putenv`` does not copy the passed
string, only a pointer to the data is stored and this data can be read even by
other threads. Content of a stack-allocated array is likely to be overwritten
-after returning from the parent function.
+after exiting from the function.
The problem can be solved by using a static array variable or dynamically
allocated memory. Even better is to avoid using ``putenv`` (it has other
@@ -1206,7 +1206,7 @@ The check corresponds to CERT rule
There is one case where the checker can report a false positive. This is when
the stack-allocated array is used at `putenv` in a function or code branch that
-does not return (calls `fork` or `exec` like function).
+does not return (process is terminated on all execution paths).
Another special case is if the `putenv` is called from function `main`. Here
the stack is deallocated at the end of the program and it should be no problem
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