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8065895: Synchronous signals during error reporting may terminate or hang VM process #39

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11 changes: 8 additions & 3 deletions hotspot/src/os/aix/vm/vmError_aix.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,6 @@ static void save_signal(int idx, int sig) {
}

int VMError::get_resetted_sigflags(int sig) {
// Handle all program errors.
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSigflags[i];
Expand All @@ -90,7 +89,6 @@ int VMError::get_resetted_sigflags(int sig) {
}

address VMError::get_resetted_sighandler(int sig) {
// Handle all program errors.
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSighandler[i];
Expand All @@ -100,12 +98,19 @@ address VMError::get_resetted_sighandler(int sig) {
}

static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {

// Unmask current signal.
sigset_t newset;
sigemptyset(&newset);
sigaddset(&newset, sig);
// and all other synchronous signals too.
for (int i = 0; i < NUM_SIGNALS; i++) {
sigaddset(&newset, SIGNALS[i]);
}
sigthreadmask(SIG_UNBLOCK, &newset, NULL);

Unimplemented();
VMError err(NULL, sig, NULL, info, ucVoid);
err.report_and_die();
}

void VMError::reset_signal_handlers() {
Expand Down
47 changes: 31 additions & 16 deletions hotspot/src/os/bsd/vm/vmError_bsd.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -63,9 +63,15 @@ void VMError::show_message_box(char *buf, int buflen) {
} while (yes);
}

// handle all synchronous program error signals which may happen during error
// reporting. They must be unblocked, caught, handled.

static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);

// Space for our "saved" signal flags and handlers
static int resettedSigflags[2];
static address resettedSighandler[2];
static int resettedSigflags[NUM_SIGNALS];
static address resettedSighandler[NUM_SIGNALS];

static void save_signal(int idx, int sig)
{
Expand All @@ -78,19 +84,19 @@ static void save_signal(int idx, int sig)
}

int VMError::get_resetted_sigflags(int sig) {
if(SIGSEGV == sig) {
return resettedSigflags[0];
} else if(SIGBUS == sig) {
return resettedSigflags[1];
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSigflags[i];
}
}
return -1;
}

address VMError::get_resetted_sighandler(int sig) {
if(SIGSEGV == sig) {
return resettedSighandler[0];
} else if(SIGBUS == sig) {
return resettedSighandler[1];
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSighandler[i];
}
}
return NULL;
}
Expand All @@ -100,16 +106,25 @@ static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
sigset_t newset;
sigemptyset(&newset);
sigaddset(&newset, sig);
sigprocmask(SIG_UNBLOCK, &newset, NULL);
// also unmask other synchronous signals
for (int i = 0; i < NUM_SIGNALS; i++) {
sigaddset(&newset, SIGNALS[i]);
}
pthread_sigmask(SIG_UNBLOCK, &newset, NULL);

VMError err(NULL, sig, NULL, info, ucVoid);
err.report_and_die();
}

void VMError::reset_signal_handlers() {
// Save sigflags for resetted signals
save_signal(0, SIGSEGV);
save_signal(1, SIGBUS);
os::signal(SIGSEGV, CAST_FROM_FN_PTR(void *, crash_handler));
os::signal(SIGBUS, CAST_FROM_FN_PTR(void *, crash_handler));
// install signal handlers for all synchronous program error signals
sigset_t newset;
sigemptyset(&newset);

for (int i = 0; i < NUM_SIGNALS; i++) {
save_signal(i, SIGNALS[i]);
os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
sigaddset(&newset, SIGNALS[i]);
}
pthread_sigmask(SIG_UNBLOCK, &newset, NULL);
}
48 changes: 32 additions & 16 deletions hotspot/src/os/linux/vm/vmError_linux.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -63,9 +63,15 @@ void VMError::show_message_box(char *buf, int buflen) {
} while (yes);
}

// handle all synchronous program error signals which may happen during error
// reporting. They must be unblocked, caught, handled.

static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);

// Space for our "saved" signal flags and handlers
static int resettedSigflags[2];
static address resettedSighandler[2];
static int resettedSigflags[NUM_SIGNALS];
static address resettedSighandler[NUM_SIGNALS];

static void save_signal(int idx, int sig)
{
Expand All @@ -78,19 +84,19 @@ static void save_signal(int idx, int sig)
}

int VMError::get_resetted_sigflags(int sig) {
if(SIGSEGV == sig) {
return resettedSigflags[0];
} else if(SIGBUS == sig) {
return resettedSigflags[1];
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSigflags[i];
}
}
return -1;
}

address VMError::get_resetted_sighandler(int sig) {
if(SIGSEGV == sig) {
return resettedSighandler[0];
} else if(SIGBUS == sig) {
return resettedSighandler[1];
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSighandler[i];
}
}
return NULL;
}
Expand All @@ -100,16 +106,26 @@ static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
sigset_t newset;
sigemptyset(&newset);
sigaddset(&newset, sig);
sigprocmask(SIG_UNBLOCK, &newset, NULL);
// also unmask other synchronous signals
for (int i = 0; i < NUM_SIGNALS; i++) {
sigaddset(&newset, SIGNALS[i]);
}
pthread_sigmask(SIG_UNBLOCK, &newset, NULL);

VMError err(NULL, sig, NULL, info, ucVoid);
err.report_and_die();
}

void VMError::reset_signal_handlers() {
// Save sigflags for resetted signals
save_signal(0, SIGSEGV);
save_signal(1, SIGBUS);
os::signal(SIGSEGV, CAST_FROM_FN_PTR(void *, crash_handler));
os::signal(SIGBUS, CAST_FROM_FN_PTR(void *, crash_handler));
// install signal handlers for all synchronous program error signals
sigset_t newset;
sigemptyset(&newset);

for (int i = 0; i < NUM_SIGNALS; i++) {
save_signal(i, SIGNALS[i]);
os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
sigaddset(&newset, SIGNALS[i]);
}
pthread_sigmask(SIG_UNBLOCK, &newset, NULL);

}
48 changes: 32 additions & 16 deletions hotspot/src/os/solaris/vm/vmError_solaris.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@

#include <sys/types.h>
#include <sys/wait.h>
#include <thread.h>
#include <signal.h>

void VMError::show_message_box(char *buf, int buflen) {
Expand Down Expand Up @@ -59,9 +60,15 @@ void VMError::show_message_box(char *buf, int buflen) {
} while (yes);
}

// handle all synchronous program error signals which may happen during error
// reporting. They must be unblocked, caught, handled.

static const int SIGNALS[] = { SIGSEGV, SIGBUS, SIGILL, SIGFPE, SIGTRAP }; // add more if needed
static const int NUM_SIGNALS = sizeof(SIGNALS) / sizeof(int);

// Space for our "saved" signal flags and handlers
static int resettedSigflags[2];
static address resettedSighandler[2];
static int resettedSigflags[NUM_SIGNALS];
static address resettedSighandler[NUM_SIGNALS];

static void save_signal(int idx, int sig)
{
Expand All @@ -74,19 +81,19 @@ static void save_signal(int idx, int sig)
}

int VMError::get_resetted_sigflags(int sig) {
if(SIGSEGV == sig) {
return resettedSigflags[0];
} else if(SIGBUS == sig) {
return resettedSigflags[1];
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSigflags[i];
}
}
return -1;
}

address VMError::get_resetted_sighandler(int sig) {
if(SIGSEGV == sig) {
return resettedSighandler[0];
} else if(SIGBUS == sig) {
return resettedSighandler[1];
for (int i = 0; i < NUM_SIGNALS; i++) {
if (SIGNALS[i] == sig) {
return resettedSighandler[i];
}
}
return NULL;
}
Expand All @@ -96,16 +103,25 @@ static void crash_handler(int sig, siginfo_t* info, void* ucVoid) {
sigset_t newset;
sigemptyset(&newset);
sigaddset(&newset, sig);
sigprocmask(SIG_UNBLOCK, &newset, NULL);
// also unmask other synchronous signals
for (int i = 0; i < NUM_SIGNALS; i++) {
sigaddset(&newset, SIGNALS[i]);
}
thr_sigsetmask(SIG_UNBLOCK, &newset, NULL);

VMError err(NULL, sig, NULL, info, ucVoid);
err.report_and_die();
}

void VMError::reset_signal_handlers() {
// Save sigflags for resetted signals
save_signal(0, SIGSEGV);
save_signal(1, SIGBUS);
os::signal(SIGSEGV, CAST_FROM_FN_PTR(void *, crash_handler));
os::signal(SIGBUS, CAST_FROM_FN_PTR(void *, crash_handler));
// install signal handlers for all synchronous program error signals
sigset_t newset;
sigemptyset(&newset);

for (int i = 0; i < NUM_SIGNALS; i++) {
save_signal(i, SIGNALS[i]);
os::signal(SIGNALS[i], CAST_FROM_FN_PTR(void *, crash_handler));
sigaddset(&newset, SIGNALS[i]);
}
thr_sigsetmask(SIG_UNBLOCK, &newset, NULL);
}
4 changes: 4 additions & 0 deletions hotspot/src/share/vm/runtime/globals.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -903,6 +903,10 @@ class CommandLineFlags {
"determines which error to provoke. See test_error_handler() " \
"in debug.cpp.") \
\
notproduct(uintx, TestCrashInErrorHandler, 0, \
"If > 0, provokes an error inside VM error handler (a secondary " \
"crash). see test_error_handler() in debug.cpp.") \
\
develop(bool, Verbose, false, \
"Print additional debugging information from other modes") \
\
Expand Down
48 changes: 42 additions & 6 deletions hotspot/src/share/vm/utilities/debug.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -337,13 +337,47 @@ bool is_error_reported() {
#ifndef PRODUCT
#include <signal.h>

typedef void (*voidfun_t)();
// Crash with an authentic sigfpe
static void crash_with_sigfpe() {
// generate a native synchronous SIGFPE where possible;
// if that did not cause a signal (e.g. on ppc), just
// raise the signal.
volatile int x = 0;
volatile int y = 1/x;
#ifndef _WIN32
raise(SIGFPE);
#endif
} // end: crash_with_sigfpe

// crash with sigsegv at non-null address.
static void crash_with_segfault() {

char* const crash_addr = (char*) get_segfault_address();
*crash_addr = 'X';

} // end: crash_with_segfault

// returns an address which is guaranteed to generate a SIGSEGV on read,
// for test purposes, which is not NULL and contains bits in every word
void* get_segfault_address() {
return (void*)
#ifdef _LP64
0xABC0000000000ABCULL;
#else
0x00000ABC;
#endif
}

void test_error_handler() {
uintx test_num = ErrorHandlerTest;
if (test_num == 0) return;
controlled_crash(ErrorHandlerTest);
}

void controlled_crash(int how) {
if (how == 0) return;

// If asserts are disabled, use the corresponding guarantee instead.
size_t n = test_num;
NOT_DEBUG(if (n <= 2) n += 2);
NOT_DEBUG(if (how <= 2) how += 2);

const char* const str = "hello";
const size_t num = (size_t)os::vm_page_size();
Expand All @@ -354,7 +388,7 @@ void test_error_handler() {
const void (*funcPtr)(void) = (const void(*)()) 0xF; // bad function pointer

// Keep this in sync with test/runtime/6888954/vmerrors.sh.
switch (n) {
switch (how) {
case 1: assert(str == NULL, "expected null");
case 2: assert(num == 1023 && *str == 'X',
err_msg("num=" SIZE_FORMAT " str=\"%s\"", num, str));
Expand All @@ -379,8 +413,10 @@ void test_error_handler() {
// There's no guarantee the bad function pointer will crash us
// so "break" out to the ShouldNotReachHere().
case 13: (*funcPtr)(); break;
case 14: crash_with_segfault(); break;
case 15: crash_with_sigfpe(); break;

default: tty->print_cr("ERROR: %d: unexpected test_num value.", n);
default: tty->print_cr("ERROR: %d: unexpected test_num value.", how);
}
ShouldNotReachHere();
}
Expand Down
18 changes: 18 additions & 0 deletions hotspot/src/share/vm/utilities/debug.hpp
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Expand Up @@ -266,6 +266,24 @@ void set_error_reported();
/* Test assert(), fatal(), guarantee(), etc. */
NOT_PRODUCT(void test_error_handler();)

// crash in a controlled way:
// how can be one of:
// 1,2 - asserts
// 3,4 - guarantee
// 5-7 - fatal
// 8 - vm_exit_out_of_memory
// 9 - ShouldNotCallThis
// 10 - ShouldNotReachHere
// 11 - Unimplemented
// 12,13 - (not guaranteed) crashes
// 14 - SIGSEGV
// 15 - SIGFPE
NOT_PRODUCT(void controlled_crash(int how);)

// returns an address which is guaranteed to generate a SIGSEGV on read,
// for test purposes, which is not NULL and contains bits in every word
NOT_PRODUCT(void* get_segfault_address();)

void pd_ps(frame f);
void pd_obfuscate_location(char *buf, size_t buflen);

Expand Down
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