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Merge pull request #4304 from poettering/notify-nul-check

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3 minor improvements for notification message handling
This commit is contained in:
Lennart Poettering 2016-10-07 18:30:53 +02:00 committed by GitHub
commit f767d3de65
1 changed files with 24 additions and 16 deletions
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40
src/core/manager.c
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@ -1720,16 +1720,15 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
return 0;
}
n = recvmsg(m->notify_fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC);
n = recvmsg(m->notify_fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC|MSG_TRUNC);
if (n < 0) {
if (!IN_SET(errno, EAGAIN, EINTR))
log_error("Failed to receive notification message: %m");
if (IN_SET(errno, EAGAIN, EINTR))
return 0; /* Spurious wakeup, try again */
/* It's not an option to return an error here since it
* would disable the notification handler entirely. Services
* wouldn't be able to send the WATCHDOG message for
* example... */
return 0;
/* If this is any other, real error, then let's stop processing this socket. This of course means we
* won't take notification messages anymore, but that's still better than busy looping around this:
* being woken up over and over again but being unable to actually read the message off the socket. */
return log_error_errno(errno, "Failed to receive notification message: %m");
}
CMSG_FOREACH(cmsg, &msghdr) {
@ -1762,13 +1761,19 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
return 0;
}
if ((size_t) n >= sizeof(buf)) {
if ((size_t) n >= sizeof(buf) || (msghdr.msg_flags & MSG_TRUNC)) {
log_warning("Received notify message exceeded maximum size. Ignoring.");
return 0;
}
/* The message should be a string. Here we make sure it's NUL-terminated,
* but only the part until first NUL will be used anyway. */
/* As extra safety check, let's make sure the string we get doesn't contain embedded NUL bytes. We permit one
* trailing NUL byte in the message, but don't expect it. */
if (n > 1 && memchr(buf, 0, n-1)) {
log_warning("Received notify message with embedded NUL bytes. Ignoring.");
return 0;
}
/* Make sure it's NUL-terminated. */
buf[n] = 0;
/* Notify every unit that might be interested, but try
@ -1941,14 +1946,17 @@ static int manager_dispatch_signal_fd(sd_event_source *source, int fd, uint32_t
for (;;) {
n = read(m->signal_fd, &sfsi, sizeof(sfsi));
if (n != sizeof(sfsi)) {
if (n >= 0) {
log_warning("Truncated read from signal fd (%zu bytes)!", n);
return 0;
}
if (n >= 0)
return -EIO;
if (errno == EINTR || errno == EAGAIN)
if (IN_SET(errno, EINTR, EAGAIN))
break;
return -errno;
/* We return an error here, which will kill this handler,
* to avoid a busy loop on read error. */
return log_error_errno(errno, "Reading from signal fd failed: %m");
}
log_received_signal(sfsi.ssi_signo == SIGCHLD ||