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SubjectRe: [PATCH] x86/asm: add __user on copy_user_handle_tail() pointers
On Thu, Feb 28, 2019 at 06:50:27PM +0000, Ben Dooks wrote:
> The copy_user_handle_tail() clearly uses both from and to as pointers
> to user-space memory. This triggers sparse warning on using the calls
> to get and put to user-space. This can be fixed easily by changing the
> call to take __user annotated pointer.s

Well, but copy_user_generic() (which ends up calling the
copy_user_handle_tail() eventually) casts those __user pointers to
(__force void *). Converting them back to __user looks strange to me.

Linus?

Leaving in the rest for reference.

> arch/x86/lib/usercopy_64.c:68:21: warning: incorrect type in argument 1 (different address spaces)
> arch/x86/lib/usercopy_64.c:68:21: expected void const volatile [noderef] <asn:1>*<noident>
> arch/x86/lib/usercopy_64.c:68:21: got char *
> arch/x86/lib/usercopy_64.c:70:21: warning: incorrect type in argument 1 (different address spaces)
> arch/x86/lib/usercopy_64.c:70:21: expected void const volatile [noderef] <asn:1>*<noident>
> arch/x86/lib/usercopy_64.c:70:21: got char *to
>
> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
> ---
> arch/x86/include/asm/uaccess_64.h | 2 +-
> arch/x86/lib/usercopy_64.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
> index a9d637bc301d..cbca2cb28939 100644
> --- a/arch/x86/include/asm/uaccess_64.h
> +++ b/arch/x86/include/asm/uaccess_64.h
> @@ -208,7 +208,7 @@ __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
> }
>
> unsigned long
> -copy_user_handle_tail(char *to, char *from, unsigned len);
> +copy_user_handle_tail(char __user *to, char __user *from, unsigned len);
>
> unsigned long
> mcsafe_handle_tail(char *to, char *from, unsigned len);
> diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
> index ee42bb0cbeb3..aa180424e77a 100644
> --- a/arch/x86/lib/usercopy_64.c
> +++ b/arch/x86/lib/usercopy_64.c
> @@ -60,7 +60,7 @@ EXPORT_SYMBOL(clear_user);
> * it is not necessary to optimize tail handling.
> */
> __visible unsigned long
> -copy_user_handle_tail(char *to, char *from, unsigned len)
> +copy_user_handle_tail(char __user *to, char __user *from, unsigned len)
> {
> for (; len; --len, to++) {
> char c;
> --
> 2.20.1
>

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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