release/19.x: Reapply "[sanitizer_common] AND signals in BlockSignals instead of deleting (#113443)" for non-Android Linux only (#115790) #116670
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…leting (llvm#113443)" for non-Android Linux only (llvm#115790) The original patch (25fd366) was reverted in 083a5cd because it broke some buildbots. This revised patch makes two changes: - Reverts to *pre-llvm#98200* behavior for Android. This avoids a build breakage on Android. - Only define KeepUnblocked if SANITIZER_LINUX: this avoids a build breakage on solaris, which does not support internal_sigdelset. N.B. Other buildbot failures were non-sanitizer tests and are therefore unrelated. Original commit message: My earlier patch llvm#98200 caused a regression because it unconditionally unblocked synchronous signals, even if the user program had deliberately blocked them. This patch fixes the issue by checking the current signal mask, as suggested by Vitaly. It also adds tests. Fixes llvm#113385 (cherry picked from commit 531acf9)
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@thurstond What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: None (llvmbot) ChangesBackport 531acf9 Requested by: @thurstond Full diff: https://github.com/llvm/llvm-project/pull/116670.diff 3 Files Affected:
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
index b9b1f496df7c98..be3b3bd94e2a58 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -160,33 +160,56 @@ void SetSigProcMask(__sanitizer_sigset_t *set, __sanitizer_sigset_t *oldset) {
CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, set, oldset));
}
+# if SANITIZER_LINUX
+// Deletes the specified signal from newset, if it is not present in oldset
+// Equivalently: newset[signum] = newset[signum] & oldset[signum]
+static void KeepUnblocked(__sanitizer_sigset_t &newset,
+ __sanitizer_sigset_t &oldset, int signum) {
+ // FIXME: https://github.com/google/sanitizers/issues/1816
+ if (SANITIZER_ANDROID || !internal_sigismember(&oldset, signum))
+ internal_sigdelset(&newset, signum);
+}
+# endif
+
// Block asynchronous signals
void BlockSignals(__sanitizer_sigset_t *oldset) {
- __sanitizer_sigset_t set;
- internal_sigfillset(&set);
-# if SANITIZER_LINUX && !SANITIZER_ANDROID
+ __sanitizer_sigset_t newset;
+ internal_sigfillset(&newset);
+
+# if SANITIZER_LINUX
+ __sanitizer_sigset_t currentset;
+
+# if !SANITIZER_ANDROID
+ // FIXME: https://github.com/google/sanitizers/issues/1816
+ SetSigProcMask(NULL, ¤tset);
+
// Glibc uses SIGSETXID signal during setuid call. If this signal is blocked
// on any thread, setuid call hangs.
// See test/sanitizer_common/TestCases/Linux/setuid.c.
- internal_sigdelset(&set, 33);
-# endif
-# if SANITIZER_LINUX
+ KeepUnblocked(newset, currentset, 33);
+# endif // !SANITIZER_ANDROID
+
// Seccomp-BPF-sandboxed processes rely on SIGSYS to handle trapped syscalls.
// If this signal is blocked, such calls cannot be handled and the process may
// hang.
- internal_sigdelset(&set, 31);
+ KeepUnblocked(newset, currentset, 31);
+# if !SANITIZER_ANDROID
// Don't block synchronous signals
- internal_sigdelset(&set, SIGSEGV);
- internal_sigdelset(&set, SIGBUS);
- internal_sigdelset(&set, SIGILL);
- internal_sigdelset(&set, SIGTRAP);
- internal_sigdelset(&set, SIGABRT);
- internal_sigdelset(&set, SIGFPE);
- internal_sigdelset(&set, SIGPIPE);
-# endif
+ // but also don't unblock signals that the user had deliberately blocked.
+ // FIXME: https://github.com/google/sanitizers/issues/1816
+ KeepUnblocked(newset, currentset, SIGSEGV);
+ KeepUnblocked(newset, currentset, SIGBUS);
+ KeepUnblocked(newset, currentset, SIGILL);
+ KeepUnblocked(newset, currentset, SIGTRAP);
+ KeepUnblocked(newset, currentset, SIGABRT);
+ KeepUnblocked(newset, currentset, SIGFPE);
+ KeepUnblocked(newset, currentset, SIGPIPE);
+# endif //! SANITIZER_ANDROID
+
+# endif // SANITIZER_LINUX
- SetSigProcMask(&set, oldset);
+ SetSigProcMask(&newset, oldset);
}
ScopedBlockSignals::ScopedBlockSignals(__sanitizer_sigset_t *copy) {
diff --git a/compiler-rt/lib/sanitizer_common/tests/CMakeLists.txt b/compiler-rt/lib/sanitizer_common/tests/CMakeLists.txt
index 2b4c15125263a9..fef8bb772e0e0d 100644
--- a/compiler-rt/lib/sanitizer_common/tests/CMakeLists.txt
+++ b/compiler-rt/lib/sanitizer_common/tests/CMakeLists.txt
@@ -15,6 +15,7 @@ set(SANITIZER_UNITTESTS
sanitizer_array_ref_test.cpp
sanitizer_atomic_test.cpp
sanitizer_bitvector_test.cpp
+ sanitizer_block_signals.cpp
sanitizer_bvgraph_test.cpp
sanitizer_chained_origin_depot_test.cpp
sanitizer_common_test.cpp
diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_block_signals.cpp b/compiler-rt/lib/sanitizer_common/tests/sanitizer_block_signals.cpp
new file mode 100644
index 00000000000000..b43648a8aef230
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_block_signals.cpp
@@ -0,0 +1,76 @@
+//===-- sanitizer_block_signals.cpp ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of sanitizer_common unit tests.
+//
+//===----------------------------------------------------------------------===//
+#include <signal.h>
+#include <stdio.h>
+
+#include "gtest/gtest.h"
+#include "sanitizer_common/sanitizer_linux.h"
+
+namespace __sanitizer {
+
+#if SANITIZER_LINUX && !SANITIZER_ANDROID
+volatile int received_sig = -1;
+
+void signal_handler(int signum) { received_sig = signum; }
+
+TEST(SanitizerCommon, NoBlockSignals) {
+ // No signals blocked
+ signal(SIGUSR1, signal_handler);
+ raise(SIGUSR1);
+ EXPECT_EQ(received_sig, SIGUSR1);
+
+ received_sig = -1;
+ signal(SIGPIPE, signal_handler);
+ raise(SIGPIPE);
+ EXPECT_EQ(received_sig, SIGPIPE);
+}
+
+TEST(SanitizerCommon, BlockSignalsPlain) {
+ // ScopedBlockSignals; SIGUSR1 should be blocked but not SIGPIPE
+ {
+ __sanitizer_sigset_t sigset = {};
+ ScopedBlockSignals block(&sigset);
+
+ received_sig = -1;
+ signal(SIGUSR1, signal_handler);
+ raise(SIGUSR1);
+ EXPECT_EQ(received_sig, -1);
+
+ received_sig = -1;
+ signal(SIGPIPE, signal_handler);
+ raise(SIGPIPE);
+ EXPECT_EQ(received_sig, SIGPIPE);
+ }
+ EXPECT_EQ(received_sig, SIGUSR1);
+}
+
+TEST(SanitizerCommon, BlockSignalsExceptPipe) {
+ // Manually block SIGPIPE; ScopedBlockSignals should not unblock this
+ sigset_t block_sigset;
+ sigemptyset(&block_sigset);
+ sigaddset(&block_sigset, SIGPIPE);
+ sigprocmask(SIG_BLOCK, &block_sigset, NULL);
+ {
+ __sanitizer_sigset_t sigset = {};
+ ScopedBlockSignals block(&sigset);
+
+ received_sig = -1;
+ signal(SIGPIPE, signal_handler);
+ raise(SIGPIPE);
+ EXPECT_EQ(received_sig, -1);
+ }
+ sigprocmask(SIG_UNBLOCK, &block_sigset, NULL);
+ EXPECT_EQ(received_sig, SIGPIPE);
+}
+#endif // SANITIZER_LINUX && !SANITIZER_ANDROID
+
+} // namespace __sanitizer
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@thurstond (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
Fixes a regression whereby the sanitizers may incorrectly unblock signals that had been blocked by the user. |
Backport 531acf9
Requested by: @thurstond