[compiler-rt] r260076 - [asan] Introduce new approach for ODR violation detection based on odr indicator symbols.
Maxim Ostapenko via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 8 00:40:01 PST 2016
Author: chefmax
Date: Mon Feb 8 02:39:59 2016
New Revision: 260076
URL: http://llvm.org/viewvc/llvm-project?rev=260076&view=rev
Log:
[asan] Introduce new approach for ODR violation detection based on odr indicator symbols.
This is a compiler-rt part of this http://reviews.llvm.org/D15642 patch. Here,
we add a new approach for ODR violation detection.
Instead of using __asan_region_is_poisoned(g->beg, g->size_with_redzone) on
global address (that would return false now due to using private alias), we can
use new globally visible indicator symbol to perform the check.
Differential Revision: http://reviews.llvm.org/D15644
Added:
compiler-rt/trunk/test/asan/TestCases/Linux/local_alias.cc
Modified:
compiler-rt/trunk/lib/asan/asan_flags.inc
compiler-rt/trunk/lib/asan/asan_globals.cc
compiler-rt/trunk/lib/asan/asan_init_version.h
compiler-rt/trunk/lib/asan/asan_interface_internal.h
compiler-rt/trunk/test/asan/TestCases/Linux/odr-violation.cc
Modified: compiler-rt/trunk/lib/asan/asan_flags.inc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_flags.inc?rev=260076&r1=260075&r2=260076&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_flags.inc (original)
+++ compiler-rt/trunk/lib/asan/asan_flags.inc Mon Feb 8 02:39:59 2016
@@ -135,3 +135,5 @@ ASAN_FLAG(const char *, suppressions, ""
ASAN_FLAG(bool, halt_on_error, true,
"Crash the program after printing the first error report "
"(WARNING: USE AT YOUR OWN RISK!)")
+ASAN_FLAG(bool, use_odr_indicator, false,
+ "Use special ODR indicator symbol for ODR violation detection")
Modified: compiler-rt/trunk/lib/asan/asan_globals.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_globals.cc?rev=260076&r1=260075&r2=260076&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_globals.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_globals.cc Mon Feb 8 02:39:59 2016
@@ -135,6 +135,70 @@ bool GetInfoForAddressIfGlobal(uptr addr
return false;
}
+enum GlobalSymbolState {
+ UNREGISTERED = 0,
+ REGISTERED = 1
+};
+
+// Check ODR violation for given global G via special ODR indicator. We use
+// this method in case compiler instruments global variables through their
+// local aliases.
+static void CheckODRViolationViaIndicator(const Global *g) {
+ u8 *odr_indicator = reinterpret_cast<u8 *>(g->odr_indicator);
+ if (*odr_indicator == UNREGISTERED) {
+ *odr_indicator = REGISTERED;
+ return;
+ }
+ // If *odr_indicator is DEFINED, some module have already registered
+ // externally visible symbol with the same name. This is an ODR violation.
+ for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
+ if (g->odr_indicator == l->g->odr_indicator &&
+ (flags()->detect_odr_violation >= 2 || g->size != l->g->size) &&
+ !IsODRViolationSuppressed(g->name))
+ ReportODRViolation(g, FindRegistrationSite(g),
+ l->g, FindRegistrationSite(l->g));
+ }
+}
+
+// Check ODR violation for given global G by checking if it's already poisoned.
+// We use this method in case compiler doesn't use private aliases for global
+// variables.
+static void CheckODRViolationViaPoisoning(const Global *g) {
+ if (__asan_region_is_poisoned(g->beg, g->size_with_redzone)) {
+ // This check may not be enough: if the first global is much larger
+ // the entire redzone of the second global may be within the first global.
+ for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
+ if (g->beg == l->g->beg &&
+ (flags()->detect_odr_violation >= 2 || g->size != l->g->size) &&
+ !IsODRViolationSuppressed(g->name))
+ ReportODRViolation(g, FindRegistrationSite(g),
+ l->g, FindRegistrationSite(l->g));
+ }
+ }
+}
+
+// Clang provides two different ways for global variables protection:
+// it can poison the global itself or it's private alias. In former
+// case we may poison same symbol multiple times, that can help us to
+// cheaply detect ODR violation: if we try to poison an already poisoned
+// global, we have ODR violation error.
+// In latter case, we poison each symbol exactly once, so we use special
+// indicator symbol to perform similar check.
+// In either case, compiler provides a special odr_indicator field to Global
+// structure, that can contain two kinds of values:
+// 1) Non-zero value. In this case, odr_indicator is an address of
+// corresponding indicator variable for given global.
+// 2) Zero. This means that we don't use private aliases for global variables
+// and can freely check ODR violation with the first method.
+//
+// This routine chooses between two different methods of ODR violation
+// detection.
+static inline bool UseODRIndicator(const Global *g) {
+ // Use ODR indicator method iff use_odr_indicator flag is set and
+ // indicator symbol address is not 0.
+ return flags()->use_odr_indicator && g->odr_indicator > 0;
+}
+
// Register a global variable.
// This function may be called more than once for every global
// so we store the globals in a map.
@@ -158,17 +222,10 @@ static void RegisterGlobal(const Global
if (flags()->detect_odr_violation) {
// Try detecting ODR (One Definition Rule) violation, i.e. the situation
// where two globals with the same name are defined in different modules.
- if (__asan_region_is_poisoned(g->beg, g->size_with_redzone)) {
- // This check may not be enough: if the first global is much larger
- // the entire redzone of the second global may be within the first global.
- for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
- if (g->beg == l->g->beg &&
- (flags()->detect_odr_violation >= 2 || g->size != l->g->size) &&
- !IsODRViolationSuppressed(g->name))
- ReportODRViolation(g, FindRegistrationSite(g),
- l->g, FindRegistrationSite(l->g));
- }
- }
+ if (UseODRIndicator(g))
+ CheckODRViolationViaIndicator(g);
+ else
+ CheckODRViolationViaPoisoning(g);
}
if (CanPoisonMemory())
PoisonRedZones(*g);
@@ -199,6 +256,12 @@ static void UnregisterGlobal(const Globa
// We unpoison the shadow memory for the global but we do not remove it from
// the list because that would require O(n^2) time with the current list
// implementation. It might not be worth doing anyway.
+
+ // Release ODR indicator.
+ if (UseODRIndicator(g)) {
+ u8 *odr_indicator = reinterpret_cast<u8 *>(g->odr_indicator);
+ *odr_indicator = UNREGISTERED;
+ }
}
void StopInitOrderChecking() {
Modified: compiler-rt/trunk/lib/asan/asan_init_version.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_init_version.h?rev=260076&r1=260075&r2=260076&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_init_version.h (original)
+++ compiler-rt/trunk/lib/asan/asan_init_version.h Mon Feb 8 02:39:59 2016
@@ -28,7 +28,8 @@ extern "C" {
// v4=>v5: changed the semantics and format of __asan_stack_malloc_ and
// __asan_stack_free_ functions.
// v5=>v6: changed the name of the version check symbol
- #define __asan_version_mismatch_check __asan_version_mismatch_check_v6
+ // v6=>v7: added 'odr_indicator' to __asan_global.
+ #define __asan_version_mismatch_check __asan_version_mismatch_check_v7
}
#endif // ASAN_INIT_VERSION_H
Modified: compiler-rt/trunk/lib/asan/asan_interface_internal.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interface_internal.h?rev=260076&r1=260075&r2=260076&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_interface_internal.h (original)
+++ compiler-rt/trunk/lib/asan/asan_interface_internal.h Mon Feb 8 02:39:59 2016
@@ -54,6 +54,7 @@ extern "C" {
uptr has_dynamic_init; // Non-zero if the global has dynamic initializer.
__asan_global_source_location *location; // Source location of a global,
// or NULL if it is unknown.
+ uptr odr_indicator; // The address of the ODR indicator symbol.
};
// These two functions should be called by the instrumented code.
Added: compiler-rt/trunk/test/asan/TestCases/Linux/local_alias.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/local_alias.cc?rev=260076&view=auto
==============================================================================
--- compiler-rt/trunk/test/asan/TestCases/Linux/local_alias.cc (added)
+++ compiler-rt/trunk/test/asan/TestCases/Linux/local_alias.cc Mon Feb 8 02:39:59 2016
@@ -0,0 +1,36 @@
+// Test that mixing instrumented and non-instrumented code doesn't lead to crash.
+// Build two modules (one is instrumented, another is not) that have globals
+// with same names. Check, that ASan doesn't crash with CHECK failure or
+// false positive global-buffer-overflow due to sanitized library poisons
+// globals from non-sanitized one.
+//
+// RUN: %clangxx_asan -DBUILD_INSTRUMENTED_DSO=1 -fPIC -shared -mllvm -asan-use-private-alias %s -o %t-INSTRUMENTED-SO.so
+// RUN: %clangxx -DBUILD_UNINSTRUMENTED_DSO=1 -fPIC -shared %s -o %t-UNINSTRUMENTED-SO.so
+// RUN: %clangxx %s -c -mllvm -asan-use-private-alias -o %t.o
+// RUN: %clangxx_asan %t.o %t-UNINSTRUMENTED-SO.so %t-INSTRUMENTED-SO.so -o %t-EXE
+// RUN: %env_asan_opts=use_odr_indicator=true %run %t-EXE
+
+#if defined (BUILD_INSTRUMENTED_DSO)
+long h = 15;
+long f = 4;
+long foo(long *p) {
+ return *p;
+}
+#elif defined (BUILD_UNINSTRUMENTED_DSO)
+long foo(long *);
+long h = 12;
+long i = 13;
+long f = 5;
+
+int bar() {
+ if (foo(&f) != 5 || foo(&h) != 12 || foo(&i) != 13)
+ return 1;
+ return 0;
+}
+#else
+extern int bar();
+
+int main() {
+ return bar();
+}
+#endif
Modified: compiler-rt/trunk/test/asan/TestCases/Linux/odr-violation.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/odr-violation.cc?rev=260076&r1=260075&r2=260076&view=diff
==============================================================================
--- compiler-rt/trunk/test/asan/TestCases/Linux/odr-violation.cc (original)
+++ compiler-rt/trunk/test/asan/TestCases/Linux/odr-violation.cc Mon Feb 8 02:39:59 2016
@@ -22,6 +22,13 @@
// RUN: echo "odr_violation:foo::G" > %t.supp
// RUN: %env_asan_opts=fast_unwind_on_malloc=0:detect_odr_violation=2:suppressions=%t.supp %run %t-ODR-EXE 2>&1 | FileCheck %s --check-prefix=DISABLED
// RUN: rm -f %t.supp
+//
+// Use private aliases for global variables: use indicator symbol to detect ODR violation.
+// RUN: %clangxx_asan -DBUILD_SO=1 -fPIC -shared -mllvm -asan-use-private-alias %s -o %t-ODR-SO.so -DSZ=100
+// RUN: %clangxx_asan -mllvm -asan-use-private-alias %s %t-ODR-SO.so -Wl,-R. -o %t-ODR-EXE
+// RUN: %env_asan_opts=fast_unwind_on_malloc=0 %run %t-ODR-EXE 2>&1 | FileCheck %s --check-prefix=DISABLED
+// RUN: %env_asan_opts=fast_unwind_on_malloc=0:use_odr_indicator=false %run %t-ODR-EXE 2>&1 | FileCheck %s --check-prefix=DISABLED
+// RUN: %env_asan_opts=fast_unwind_on_malloc=0:use_odr_indicator=true not %run %t-ODR-EXE 2>&1 | FileCheck %s
// GNU driver doesn't handle .so files properly.
// REQUIRES: Clang
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