Eric Biggers <ebigg...@kernel.org> writes:
> Hi Eric,
>
> The following commit, which went into v4.20, introduced undefined behavior
> when
> sys_rt_sigqueueinfo() is called with sig=0:
Ouch. Good catch.
It looks like the fix is just to do:
diff --git a/include/linux/signal.h b/include/linux/signal.h
index f428e86f4800..b5d99482d3fe 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -388,7 +388,7 @@ extern bool unhandled_signal(struct task_struct *tsk, int
sig);
#endif
#define siginmask(sig, mask) \
- ((sig) < SIGRTMIN && (rt_sigmask(sig) & (mask)))
+ ((sig) > 0 && (sig) < SIGRTMIN && (rt_sigmask(sig) & (mask)))
#define SIG_KERNEL_ONLY_MASK (\
rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP))
As gcc is smart enough to combine those two range tests into a single
comparison. That will ensure the undefined behavior does not byte
anyone else.
I will see about whipping up a proper patch.
Eric
