commit 6b97a5a843341b5ea2a9039bdd5290d524a44cd4 Author: teor teor@torproject.org Date: Wed Sep 4 14:50:09 2019 +1000

backtrace: Disable signal handlers in remove_bt_handler()

Fixes bug 31614; bugfix on 0.2.5.2-alpha. --- src/lib/err/backtrace.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/lib/err/backtrace.c b/src/lib/err/backtrace.c index 1d1b3bcfa..77dc6b8cb 100644 --- a/src/lib/err/backtrace.c +++ b/src/lib/err/backtrace.c @@ -190,13 +190,15 @@ 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 +237,19 @@ 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); + } } #endif /* defined(USE_BACKTRACE) */