Messages in this thread | | | Subject | Re: [PATCH v3] Add kernel config option for tweaking kernel behavior. | From | Tetsuo Handa <> | Date | Sun, 19 Apr 2020 00:08:13 +0900 |
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On 2020/04/18 23:39, Greg Kroah-Hartman wrote: >> 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 :(
Then, what about "twist" ?
>> @@ -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?
Maybe someday we update this filter more fine-grained. But I think this granularity is what syzkaller wants for now. The ctrl-alt-del ( k_spec() => fn_boot_it() => ctrl_alt_del()) is simply one of them. There was RCU stall report caused by repeating SysRq-t from this path ( k_spec() => fn_show_state() => show_state()) due to too much printk() calls.
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