Commit c1bf4260 authored by Nick Mathewson's avatar Nick Mathewson 🎨
Browse files

Merge remote-tracking branch 'tor-github/pr/1302' into maint-0.4.1

parents d4dde249 749c2e17
o Minor bugfixes (logging):
- Disable backtrace signal handlers when shutting down tor.
Fixes bug 31614; bugfix on 0.2.5.2-alpha.
- Add a missing check for HAVE_PTHREAD_H, because the backtrace code uses
mutexes. Fixes bug 31614; bugfix on 0.2.5.2-alpha.
o Documentation:
- Explain why we can't destroy the backtrace buffer mutex. Explain why
we don't need to destroy the log mutex.
Closes ticket 31736.
......@@ -57,7 +57,8 @@
#include "lib/err/torerr.h"
#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \
defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION)
defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION) && \
defined(HAVE_PTHREAD_H)
#define USE_BACKTRACE
#endif
......@@ -190,13 +191,15 @@ dump_stack_symbols_to_error_fds(void)
backtrace_symbols_fd(cb_buf, (int)depth, fds[i]);
}
/* The signals that we want our backtrace handler to trap */
static int trap_signals[] = { SIGSEGV, SIGILL, SIGFPE, SIGBUS, SIGSYS,
SIGIO, -1 };
/** Install signal handlers as needed so that when we crash, we produce a
* useful stack trace. Return 0 on success, -errno on failure. */
static int
install_bt_handler(const char *software)
{
int trap_signals[] = { SIGSEGV, SIGILL, SIGFPE, SIGBUS, SIGSYS,
SIGIO, -1 };
int i, rv=0;
strncpy(bt_version, software, sizeof(bt_version) - 1);
......@@ -235,6 +238,23 @@ install_bt_handler(const char *software)
static void
remove_bt_handler(void)
{
int i;
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_DFL;
sigfillset(&sa.sa_mask);
for (i = 0; trap_signals[i] >= 0; ++i) {
/* remove_bt_handler() is called on shutdown, from low-level code.
* It's not a fatal error, so we just ignore it. */
(void)sigaction(trap_signals[i], &sa, NULL);
}
/* cb_buf_mutex is statically initialised, so we can not destroy it.
* If we destroy it, and then re-initialise tor, all our backtraces will
* fail. */
}
#endif /* defined(USE_BACKTRACE) */
......
......@@ -806,7 +806,10 @@ logs_free_all(void)
}
/* We _could_ destroy the log mutex here, but that would screw up any logs
* that happened between here and the end of execution. */
* that happened between here and the end of execution.
* If tor is re-initialized, log_mutex_initialized will still be 1. So we
* won't trigger any undefined behaviour by trying to re-initialize the
* log mutex. */
}
/** Remove and free the log entry <b>victim</b> from the linked-list
......
......@@ -294,6 +294,7 @@ sb_rt_sigaction(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
unsigned i;
int rc;
int param[] = { SIGINT, SIGTERM, SIGPIPE, SIGUSR1, SIGUSR2, SIGHUP, SIGCHLD,
SIGSEGV, SIGILL, SIGFPE, SIGBUS, SIGSYS, SIGIO,
#ifdef SIGXFSZ
SIGXFSZ
#endif
......
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