From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH v2, variant B] tty: nozomi: avoid sprintf buffer overflow Date: Tue, 29 Nov 2016 20:19:37 +0100 Message-ID: <20161129191937.GA3155@kroah.com> References: <20161129115104.1755786-1-arnd@arndb.de> <20161129115104.1755786-2-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20161129115104.1755786-2-arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: Jiri Slaby , linux-kernel@vger.kernel.org, Peter Hurley , linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org On Tue, Nov 29, 2016 at 12:51:04PM +0100, Arnd Bergmann wrote: > Testing with a gcc-7 snapshot produced an internal compiler error > for this file: > > drivers/tty/nozomi.c: In function 'receive_flow_control': > drivers/tty/nozomi.c:919:12: internal compiler error: in get_substring_ranges_for_loc, at input.c:1388 > static int receive_flow_control(struct nozomi *dc) > > I've reported this at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78569 > but also noticed that the code line contains a stack overflow, as it prints > a string into a slightly shorter fixed-length 'tmp' variable. > > A lot of the code here is unnecessary and can be expressed in a simpler > way, relying on the fact that removing the 'DEBUG' macro will also get > rid of all pr_debug() calls. This change should not change any of the > output but avoids both the stack overflow and the gcc crash. I like this, but I don't think this patch went far enough, we should get rid of the "special" macro entirely and just use dev_dbg() everywhere as the dynamic debugging interface is exactly for this type of thing (you can turn them on or off per-line, no need for odd "levels".) So I'll take this patch now to remove the obvious error, but follow-on patches to fix it up "correctly" would be great. thanks, greg k-h