On Fri, 2014-05-23 at 20:51 -0400, Dave Jones wrote: > On Fri, May 23, 2014 at 07:09:03PM +1000, Michael Ellerman wrote: > > In output() we sprintf() the result of find_pid_slot(). We print the pid > > slot to the buffer with %u and have space for two digits of pid slot. > > find_pid_slot() potentially returns PIDSLOT_NOT_FOUND (-1), which when > > printed with %u is 4294967295 - ten digits. > > > > Fix it two ways, use snprintf() - truncated output is better than a > > buffer overflow. And allocate more space in the buffer, 32 bytes is a > > nice round size, and gives us space for everything. > > heh, this has been nagging me from time to time, but it wasn't a problem > until recently. I'm curious why you're hitting that PIDSLOT_NOT_FOUND > case though, as it's a "should never happen" case. Yeah, I figured it wasn't meant to happen. > Anyway, it's the right thing to do, so I pushed this out. > > > @@ -311,7 +311,7 @@ void output(unsigned char level, const char *fmt, ...) > > unsigned int slot; > > > > slot = find_pid_slot(pid); > > - sprintf(child_prefix, "[child%u:%u]", slot, pid); > > + snprintf(child_prefix, sizeof(child_prefix), "[child%u:%u]", slot, pid); > > prefix = child_prefix; > > might be worth it to add something later to print PIDSLOT_NOT_FOUND entries as '?' > rather than 4294967295. I thought about it, but figured "4294967295" was actually a good eye-catcher. If you'd prefer "?" then let me know and I can do a patch for that. I haven't actually hit that case again though. cheers -- To unsubscribe from this list: send the line "unsubscribe trinity" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
