Messages in this thread | | | From | "Eric W. Biederman" <> | Date | Fri, 07 Jan 2022 00:47:18 -0600 | Subject | Re: [PATCH] signal: strict valid signal check |
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Hongchen Zhang <zhanghongchen@loongson.cn> writes:
> The max usable signal number is limited by both _NSIG and task's > exit_code, and the max valid signal number encoded in task's > exit_code is 127. On the other hand _NSIG is normally power of 2, > so limit the rule in valid_signal to check a valid signal number.
A quick look reveals this only affects mips.
If you have copied that silliness from mips for your new architecture I would advise against it. That just seems to make sigset_t twice as big as it needs to be for no good reason.
What seems reasonable is to fix mips to only support 127 signals (with the same sigset_t size) and to add "BUILD_BUG_ON(_NSIG <= 127);" along with your comment somewhere in kernel/signal.c
Eric
> Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn> > --- > include/linux/signal.h | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/include/linux/signal.h b/include/linux/signal.h > index a6db6f2..9f1972e 100644 > --- a/include/linux/signal.h > +++ b/include/linux/signal.h > @@ -270,7 +270,11 @@ static inline void init_sigpending(struct sigpending *sig) > /* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */ > static inline int valid_signal(unsigned long sig) > { > - return sig <= _NSIG ? 1 : 0; > + /* max usable signal number is limited by both _NSIG and task's > + * exit_code, and the max available signal number encoded in > + * task's exit_code is 127. > + */ > + return sig <= min(_NSIG, 127) ? 1 : 0; > } > > struct timespec;
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