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authorKamil Rytarowski <n54@gmx.com>2017-12-06 21:57:39 +0000
committerKamil Rytarowski <n54@gmx.com>2017-12-06 21:57:39 +0000
commit2f6cd8dba8b7727abe37f8680dd6ad5a03b47158 (patch)
tree8134ccb3e64337d38e842351d782bc5aa1957ed1 /lib
parentd4f4f7cd131af547f3d94219c1f486534fec2e60 (diff)
Correct atexit(3) support in MSan/NetBSD
Summary: The NetBSD specific implementation of cxa_atexit() does not preserve the 2nd argument if dso is equal to NULL. Changes: - Split paths of handling intercepted __cxa_atexit() and atexit(3). This affects all supported Operating Systems. - Add a local stack-like structure to hold the __cxa_atexit() context. atexit(3) is documented in the C standard as calling callback from the earliest to the oldest entry. This path also fixes potential ABI problem of passing an argument to a function from the atexit(3) callback mechanism. - Allow usage of global vars with ctors in interceptors. This allows to use Vector without automatic cleaning up the structures. This code has been modeled after TSan implementation for the same functions. Sponsored by <The NetBSD Foundation> Reviewers: joerg, dvyukov, eugenis, vitalybuka, kcc Reviewed By: vitalybuka Subscribers: llvm-commits, #sanitizers Tags: #sanitizers Differential Revision: https://reviews.llvm.org/D40714 git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@319967 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/msan/msan_interceptors.cc66
1 files changed, 63 insertions, 3 deletions
diff --git a/lib/msan/msan_interceptors.cc b/lib/msan/msan_interceptors.cc
index ae9c89494..69c1aeb73 100644
--- a/lib/msan/msan_interceptors.cc
+++ b/lib/msan/msan_interceptors.cc
@@ -33,6 +33,7 @@
#include "sanitizer_common/sanitizer_libc.h"
#include "sanitizer_common/sanitizer_linux.h"
#include "sanitizer_common/sanitizer_tls_get_addr.h"
+#include "sanitizer_common/sanitizer_vector.h"
#if SANITIZER_NETBSD
#define gettimeofday __gettimeofday50
@@ -1121,23 +1122,78 @@ struct MSanAtExitRecord {
void *arg;
};
-void MSanAtExitWrapper(void *arg) {
+struct InterceptorContext {
+ BlockingMutex atexit_mu;
+ Vector<struct MSanAtExitRecord *> AtExitStack;
+
+ InterceptorContext()
+ : AtExitStack() {
+ }
+};
+
+static ALIGNED(64) char interceptor_placeholder[sizeof(InterceptorContext)];
+InterceptorContext *interceptor_ctx() {
+ return reinterpret_cast<InterceptorContext*>(&interceptor_placeholder[0]);
+}
+
+void MSanAtExitWrapper() {
+ MSanAtExitRecord *r;
+ {
+ BlockingMutexLock l(&interceptor_ctx()->atexit_mu);
+
+ uptr element = interceptor_ctx()->AtExitStack.Size() - 1;
+ r = interceptor_ctx()->AtExitStack[element];
+ interceptor_ctx()->AtExitStack.PopBack();
+ }
+
+ UnpoisonParam(1);
+ ((void(*)())r->func)();
+ InternalFree(r);
+}
+
+void MSanCxaAtExitWrapper(void *arg) {
UnpoisonParam(1);
MSanAtExitRecord *r = (MSanAtExitRecord *)arg;
r->func(r->arg);
InternalFree(r);
}
+static int setup_at_exit_wrapper(void(*f)(), void *arg, void *dso);
+
+// Unpoison argument shadow for C++ module destructors.
+INTERCEPTOR(int, atexit, void (*func)()) {
+ if (msan_init_is_running) return REAL(atexit)(func);
+ return setup_at_exit_wrapper((void(*)())func, 0, 0);
+}
+
// Unpoison argument shadow for C++ module destructors.
INTERCEPTOR(int, __cxa_atexit, void (*func)(void *), void *arg,
void *dso_handle) {
if (msan_init_is_running) return REAL(__cxa_atexit)(func, arg, dso_handle);
+ return setup_at_exit_wrapper((void(*)())func, arg, dso_handle);
+}
+
+static int setup_at_exit_wrapper(void(*f)(), void *arg, void *dso) {
ENSURE_MSAN_INITED();
MSanAtExitRecord *r =
(MSanAtExitRecord *)InternalAlloc(sizeof(MSanAtExitRecord));
- r->func = func;
+ r->func = (void(*)(void *a))f;
r->arg = arg;
- return REAL(__cxa_atexit)(MSanAtExitWrapper, r, dso_handle);
+ int res;
+ if (!dso) {
+ // NetBSD does not preserve the 2nd argument if dso is equal to 0
+ // Store ctx in a local stack-like structure
+
+ BlockingMutexLock l(&interceptor_ctx()->atexit_mu);
+
+ res = REAL(__cxa_atexit)((void (*)(void *a))MSanAtExitWrapper, 0, 0);
+ if (!res) {
+ interceptor_ctx()->AtExitStack.PushBack(r);
+ }
+ } else {
+ res = REAL(__cxa_atexit)(MSanCxaAtExitWrapper, r, dso);
+ }
+ return res;
}
static void BeforeFork() {
@@ -1535,6 +1591,9 @@ namespace __msan {
void InitializeInterceptors() {
static int inited = 0;
CHECK_EQ(inited, 0);
+
+ new(interceptor_ctx()) InterceptorContext();
+
InitializeCommonInterceptors();
InitializeSignalInterceptors();
@@ -1650,6 +1709,7 @@ void InitializeInterceptors() {
INTERCEPT_FUNCTION(pthread_join);
INTERCEPT_FUNCTION(tzset);
+ INTERCEPT_FUNCTION(atexit);
INTERCEPT_FUNCTION(__cxa_atexit);
INTERCEPT_FUNCTION(shmat);
INTERCEPT_FUNCTION(fork);