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signal: Reduce copy_siginfo to just a memcpy

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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>
This commit is contained in:
Eric W. Biederman 2017-07-19 21:30:42 -05:00
parent 7771c66457
commit 8c36fdf5ed
1 changed files with 2 additions and 6 deletions
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6
include/linux/signal.h
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@ -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);