openssh/openssh-5.9p1-blocksigalrm.diff
2011-12-26 07:09:33 +00:00

44 lines
1.3 KiB
Diff

Index: log.c
===================================================================
--- log.c.orig
+++ log.c
@@ -51,6 +51,7 @@
#include "xmalloc.h"
#include "log.h"
+#include <signal.h>
static LogLevel log_level = SYSLOG_LEVEL_INFO;
static int log_on_stderr = 1;
@@ -336,6 +337,7 @@ do_log(LogLevel level, const char *fmt,
char fmtbuf[MSGBUFSIZ];
char *txt = NULL;
int pri = LOG_INFO;
+ sigset_t nset, oset;
int saved_errno = errno;
log_handler_fn *tmp_handler;
@@ -387,6 +389,14 @@ do_log(LogLevel level, const char *fmt,
snprintf(msgbuf, sizeof msgbuf, "%s\r\n", fmtbuf);
write(STDERR_FILENO, msgbuf, strlen(msgbuf));
} else {
+ /* Prevent a race between the grace_alarm
+ * which writes a log message and terminates
+ * and main sshd code that leads to deadlock
+ * as syslog is not async safe.
+ */
+ sigemptyset(&nset);
+ sigaddset(&nset, SIGALRM);
+ sigprocmask(SIG_BLOCK, &nset, &oset);
#if defined(HAVE_OPENLOG_R) && defined(SYSLOG_DATA_INIT)
openlog_r(argv0 ? argv0 : __progname, LOG_PID, log_facility, &sdata);
syslog_r(pri, &sdata, "%.500s", fmtbuf);
@@ -396,6 +406,7 @@ do_log(LogLevel level, const char *fmt,
syslog(pri, "%.500s", fmtbuf);
closelog();
#endif
+ sigprocmask(SIG_SETMASK, &oset, NULL);
}
errno = saved_errno;
}