Commit 8c36fdf5 authored Jul 19, 2017 by Eric W. Biederman

signal: Reduce copy_siginfo to just a memcpy

The savings for copying just part of struct siginfo appears to be in the
noise on modern machines. So remove this ``optimization'' and simplify the code.

At the same time mark the second parameter as constant so there is no confusion
as to which direction the copy will go.

This ensures that a fully initialized siginfo that is sent ends up as
a fully initialized siginfo on the signal queue. This full initialization
ensures even confused code won't copy unitialized data to userspace, and
it prepares for turning copy_siginfo_to_user into a simple copy_to_user.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

parent 7771c664

include/linux/signal.h

+2 −6

Original line number	Diff line number	Diff line
		@@ -11,13 +11,9 @@ struct task_struct;
		/* for sysctl */
		extern int print_fatal_signals;

		static inline void copy_siginfo(struct siginfo to, struct siginfo from)
		static inline void copy_siginfo(struct siginfo to, const struct siginfo from)
		{
		if (from->si_code < 0)
		memcpy(to, from, sizeof(*to));
		else
		/* _sigchld is currently the largest know union member */
		memcpy(to, from, __ARCH_SI_PREAMBLE_SIZE + sizeof(from->_sifields._sigchld));
		}

		int copy_siginfo_to_user(struct siginfo __user to, const struct siginfo from);

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