Messages in this thread |  | | Date | Mon, 16 Dec 2019 15:18:34 -0500 | From | "Theodore Y. Ts'o" <> | Subject | Re: [PATCH] kconfig: Add kernel config option for fuzz testing. |
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On Tue, Dec 17, 2019 at 12:35:00AM +0900, Tetsuo Handa wrote: > >> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > >> index 1ef6f75d92f1..9a2f95a78fef 100644 > >> --- a/kernel/printk/printk.c > >> +++ b/kernel/printk/printk.c > >> @@ -1198,6 +1198,14 @@ MODULE_PARM_DESC(ignore_loglevel, > >> > >> static bool suppress_message_printing(int level) > >> { > >> +#ifdef CONFIG_KERNEL_BUILT_FOR_FUZZ_TESTING > >> + /* > >> + * Changing console_loglevel causes "no output". But ignoring > >> + * console_loglevel is easier than preventing change of > >> + * console_loglevel. > >> + */ > >> + return (level >= CONSOLE_LOGLEVEL_DEFAULT && !ignore_loglevel); > >> +#endif > > > > I don't understand the need for this change at all. > > this case was too hard to blacklist, as explained at > https://lore.kernel.org/lkml/4d1a4b51-999b-63c6-5ce3-a704013cecb6@i-love.sakura.ne.jp/ . > syz_execute_func() can find deeper bug by executing arbitrary binary code, but > we cannot blacklist specific syscalls/arguments for syz_execute_func() testcases. > Unless we guard on the kernel side, we won't be able to re-enable syz_execute_func() > testcases.
I looked at the reference, but I didn't see the explanation in the above link about why it was "too hard to blacklist". In fact, it looks like a bit earlier in the thread, Dmitry stated that adding this find of blacklist "is not hard"?
https://lore.kernel.org/lkml/CACT4Y+Z_+H09iOPzSzJfs=_D=dczk22gL02FjuZ6HXO+p0kRyA@mail.gmail.com/
I suspect that adding whack-a-mole in the kernel is going to be just as hard/annoying as adding it in Syzkaller.... The question is under which rug are we proposing to hide the dirt? :-)
- Ted
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