Re: git: 005aa1743b42 - main - modules: bzero the modspecific_t
Date: Sat, 01 Jul 2023 23:13:16 UTC
On Sat, Jul 01, 2023 at 10:59:22PM +0000, Ka Ho Ng wrote:
> The branch main has been updated by khng:
>
> URL: https://cgit.FreeBSD.org/src/commit/?id=005aa1743b42b52fbd49b9d5ec44816902b6ee9f
>
> commit 005aa1743b42b52fbd49b9d5ec44816902b6ee9f
> Author: Ka Ho Ng <khng@FreeBSD.org>
> AuthorDate: 2023-07-01 19:41:53 +0000
> Commit: Ka Ho Ng <khng@FreeBSD.org>
> CommitDate: 2023-07-01 22:58:46 +0000
>
> modules: bzero the modspecific_t
>
> Per https://reviews.llvm.org/D68115, only the first field is
> zero-initialized, meanwhile other fields are undef.
This is not true.
>
> The pattern can be observed on clang as well, that when
> -ftrivial-auto-var-init=pattern is specified 0xaa is filled for
> non-active fields, otherwise they are zero-initialized.
What are non-active fields?
All fields with implicit initializers
"shall be initialized implicitly the same as
objects that have static storage duration."
I do not think this is required for padding.
> Technically both are acceptable when using clang. However it
> would be good to simply bzero the modspecific_t in such case to
> be strict to the standard.
>
> MFC with: 2cab2d43b83b
> MFC after: 1 day
Min MFC period is 3 days.
> Sponsored by: Juniper Networks, Inc.
> Reviewed by: delphij
> Differential Revision: https://reviews.freebsd.org/D40830
> ---
> sys/kern/kern_syscalls.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/sys/kern/kern_syscalls.c b/sys/kern/kern_syscalls.c
> index 234e51cfd280..0b51edf5e985 100644
> --- a/sys/kern/kern_syscalls.c
> +++ b/sys/kern/kern_syscalls.c
> @@ -173,9 +173,10 @@ kern_syscall_module_handler(struct sysent *sysents, struct module *mod,
> int what, void *arg)
> {
> struct syscall_module_data *data = arg;
> - modspecific_t ms = { 0 };
> + modspecific_t ms;
> int error;
>
> + bzero(&ms, sizeof(ms));
> switch (what) {
> case MOD_LOAD:
> error = kern_syscall_register(sysents, data->offset,