Re: [PATCH] PM / hibernate: Remove unnecessary compat ioctl overrides

Rafael J. Wysocki
2020-03-15T02:57:26Z

On Sunday, March 8, 2020 4:27:01 AM CET Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> Since the SNAPSHOT_GET_IMAGE_SIZE, SNAPSHOT_AVAIL_SWAP_SIZE, and
> SNAPSHOT_ALLOC_SWAP_PAGE ioctls produce an loff_t result, and loff_t is
> always 64-bit even in the compat case, there's no reason to have the
> special compat handling for these ioctls. Just remove this unneeded
> code so that these ioctls call into snapshot_ioctl() directly, doing
> just the compat_ptr() conversion on the argument.
>
> (This unnecessary code was also causing a KMSAN false positive.)
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> kernel/power/user.c | 16 +---------------
> 1 file changed, 1 insertion(+), 15 deletions(-)
>
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index 77438954cc2b..58ed9478787f 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -409,21 +409,7 @@ snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> switch (cmd) {
> case SNAPSHOT_GET_IMAGE_SIZE:
> case SNAPSHOT_AVAIL_SWAP_SIZE:
> - case SNAPSHOT_ALLOC_SWAP_PAGE: {
> - compat_loff_t __user *uoffset = compat_ptr(arg);
> - loff_t offset;
> - mm_segment_t old_fs;
> - int err;
> -
> - old_fs = get_fs();
> - set_fs(KERNEL_DS);
> - err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
> - set_fs(old_fs);
> - if (!err && put_user(offset, uoffset))
> - err = -EFAULT;
> - return err;
> - }
> -
> + case SNAPSHOT_ALLOC_SWAP_PAGE:
> case SNAPSHOT_CREATE_IMAGE:
> return snapshot_ioctl(file, cmd,
> (unsigned long) compat_ptr(arg));
>

Applied as 5.7 material, thanks!