Messages in this thread | | | Date | Sat, 18 Apr 2020 16:39:24 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH v3] Add kernel config option for tweaking kernel behavior. |
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On Sat, Apr 18, 2020 at 11:28:22PM +0900, Tetsuo Handa wrote: > On 2020/04/13 17:14, Greg Kroah-Hartman wrote: > >> @@ -2223,4 +2223,15 @@ config HYPERV_TESTING > >> > >> endmenu # "Kernel Testing and Coverage" > >> > >> +menuconfig TWEAK_KERNEL_BEHAVIOR > >> + bool "Tweak kernel behavior" > >> + help > >> + Saying Y here allows modifying kernel behavior via kernel > >> + config options which will become visible by selecting this > >> + config option. > > > > This "help" text really only says "say Y here to allow for some config > > options". It doesn't explain what these are for, or why anyone would > > select them, or what type of options are here at all. > > > > I don't see how this option, by just looking at it, relates to your goal > > of doing things to make fuzzers' lives easier. > > Well, we could add some more text (like shown below), but this option itself > is neutral. This option is not limiting the target to fuzzers. > Below 3 patches are an example of "a set of fine-grained configs" with > "some umbrella uber-config" approach. Linus, are you OK with this approach?
Note, the word "tweak" is usually used where people want to get the most performance out of a system, while here you are using it to remove functionality out of the system. You might want to pick a different word, naming is hard :(
Anyway, a comment on your patch:
> >From f7f668896e188217b50c50a31c4ad1acb7556b36 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Date: Sat, 18 Apr 2020 22:39:38 +0900 > Subject: [PATCH 2/3] tweak: Allow disabling k_spec() function in drivers/tty/vt/keyboard.c > > syzbot is reporting unexpected kernel reboots [1]. This seems to be > caused by triggering Ctrl-Alt-Del event via k_spec() function in > drivers/tty/vt/keyboard.c file, for the console output includes normal > restart sequence. Therefore, allow disabling only k_spec() function > in order to allow fuzzers to examine the remaining part in that file. > > [1] https://syzkaller.appspot.com/bug?id=321861b1588b44d064b779b92293c5d55cfe8430 > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > --- > drivers/tty/vt/keyboard.c | 2 ++ > lib/Kconfig.tewak | 7 +++++++ > 2 files changed, 9 insertions(+) > > diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c > index 15d33fa0c925..f08855c4c5ba 100644 > --- a/drivers/tty/vt/keyboard.c > +++ b/drivers/tty/vt/keyboard.c > @@ -633,6 +633,8 @@ static void k_spec(struct vc_data *vc, unsigned char value, char up_flag) > kbd->kbdmode == VC_OFF) && > value != KVAL(K_SAK)) > return; /* SAK is allowed even in raw mode */ > + if (IS_ENABLED(CONFIG_TWEAK_DISABLE_KBD_K_SPEC_HANDLER)) > + return;
Are you sure this is correct? It seems like you just cut off a number of other keyboard function handlers instead of just the ctrl-alt-del functionality. Did you really want to do that?
thanks,
greg k-h
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