log: check for i/o error with vsnprintf()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/log.c b/src/lxc/log.c
index 16b79c09d174e8a3253f804af5195e3e0ed85c76..351b191fb93d938d92e712db9a75d8b474009ef5 100644 (file)
--- a/src/lxc/log.c
+++ b/src/lxc/log.c
@@ -264,7 +264,7 @@ static int log_append_logfile(const struct lxc_log_appender *appender,
 {
        char buffer[LXC_LOG_BUFFER_SIZE];
        char date_time[LXC_LOG_TIME_SIZE];
-       int n;
+       int n, ret;
        int fd_to_use = -1;
 
 #ifndef NO_LXC_CONF
@@ -295,8 +295,13 @@ static int log_append_logfile(const struct lxc_log_appender *appender,
        if (n < 0)
                return n;
 
-       if ((size_t)n < (sizeof(buffer) - 1))
-               n += vsnprintf(buffer + n, sizeof(buffer) - n, event->fmt, *event->vap);
+       if ((size_t)n < (sizeof(buffer) - 1)) {
+               ret = vsnprintf(buffer + n, sizeof(buffer) - n, event->fmt, *event->vap);
+               if (ret < 0)
+                       return 0;
+
+               n += ret;
+       }
 
        if ((size_t)n >= sizeof(buffer))
                n = sizeof(buffer) - 1;