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Collecting dumps can cause process termination with "*** buffer overflow detected ***" message #6

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Collecting dumps can cause process termination with "*** buffer overflow detected ***" message #6

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34 changes: 19 additions & 15 deletions threadstacks/signal_handler.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#include <sys/timerfd.h>
#include <sys/types.h>
#include <unistd.h>
#include <poll.h>

#include <algorithm>
#include <cstring>
Expand Down Expand Up @@ -386,28 +387,31 @@ auto StackTraceCollector::Collect(std::string* error) -> std::vector<Result> {
// process to become non-responsive.
int flags = fcntl(pipe_fd[0], F_GETFL, 0);
fcntl(pipe_fd[0], F_SETFL, flags | O_NONBLOCK);
fd_set read_fds;
FD_ZERO(&read_fds);
FD_SET(pipe_fd[0], &read_fds);
FD_SET(timer_fd, &read_fds);
auto max_fd = std::max(pipe_fd[0], timer_fd) + 1;
auto ret = select(max_fd, &read_fds, nullptr, nullptr, nullptr);
pollfd pipeAndTimerPollFd[2];
pipeAndTimerPollFd[0].fd = pipe_fd[0];
pipeAndTimerPollFd[0].events = POLLIN;
pipeAndTimerPollFd[1].fd = timer_fd;
pipeAndTimerPollFd[1].events = POLLIN;
const int noTimeout = -1;
auto ret = poll(pipeAndTimerPollFd, 2, noTimeout);
if (ret == -1) {
std::cerr << "select(...) failed, will try again" << std::endl; // errno
std::cerr << "poll(...) failed, will try again" << std::endl;
} else if (ret == 0) {
// We should never encounter this case as we use an infinite timeout in
// the select syscall.
std::cerr << "No file descriptors ready, will try again"
<< std::endl; // errno
} else if (FD_ISSET(timer_fd, &read_fds)) {
// This should never happen as 0 means timeout but no timeout has been given!
std::cerr << "poll() returned 0 even though no timeout was given, will try again" << std::endl;
} else if(pipeAndTimerPollFd[1].revents == POLLIN) {
std::cerr << "Failed to get all (" << tids.size()
<< ") the stacktrace acks within timeout. Got only " << acks
<< std::endl; // errno
<< ") the stacktrace messages within timeout. Got only " << acks
<< std::endl;
error->assign("Failed to get all (" + std::to_string(tids.size()) +
") stacktraces within timeout. Got only " +
std::to_string(acks));
return {};
} else if (FD_ISSET(pipe_fd[0], &read_fds)) {
} else {
if(pipeAndTimerPollFd[0].revents != POLLIN) {
std::cerr << "Error calling poll(), expected the pipe to be ready for reading!" << std::endl;
}

char ch;
auto num_read = read(pipe_fd[0], &ch, sizeof(ch));
if (-1 == num_read) {
Expand Down