Messages in this thread | | | Date | Fri, 26 Apr 2019 16:27:10 +0200 | From | Petr Mladek <> | Subject | Re: [PATCH v7 00/10] vsprintf: Prevent silent crashes and consolidate error handling |
| |
On Fri 2019-04-26 16:02:04, Andy Shevchenko wrote: > On Wed, Apr 24, 2019 at 03:53:06PM +0200, Petr Mladek wrote: > > On Fri 2019-04-19 10:51:12, Sergey Senozhatsky wrote: > > > On (04/17/19 13:53), Petr Mladek wrote: > > > > Crash in vsprintf() might be silent when it happens under logbuf_lock > > > > in vprintk_emit(). This patch set prevents most of the crashes by probing > > > > the address. The check is done only by %s and some %p* specifiers that need > > > > to dereference the address. > > > > > > > > Only the first byte of the address is checked to keep it simple. It should > > > > be enough to catch most problems. > > > > > > > > The check is explicitly done in each function that does the dereference. > > > > It helps to avoid the questionable strchr() of affected specifiers. This > > > > change motivated me to do some preparation patches that consolidated > > > > the error handling and cleaned the code a bit. > > > > > > The patch set looks OK to me. > > > > > > I got confused by 'pC?' error string, but once you start looking > > > at it as a regex (? - zero or one occurrences) things look OK. > > > Regex in dmesg/serial output might be something very new to people, > > > stack traces, after all, is a rather common error reporting mechanism. > > > So the previous "WARN_ON() + exact unrecognized fmt[N] char" was not > > > totally awful or wrong (well, it was, before we introduced printk_safe()), > > > but I don't have strong objections against that new regex thing. > > > > > > FWIW, > > > Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > > > > Thanks a lot for review. > > > > I have pushed the entire patchset into printk.git, > > branch for-5.2-vsprintf-hardening to get some > > test coverage via linux-next. > > > > I still expect some feedback, especially from Andy > > who seems to have a vacation these days. > > I think that Andy wanted these changes rather sooner > > than later, so I hope that he would be fine with it. > > I could take it back in case of disagreement. > > They are good enough to me, thanks! > FWIW, > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Thanks a lot. I have added the tag to the commits in printk.git, branch for-5.2-vsprintf-hardening.
Best Regards, Petr
| |