Re: [PATCH] nvmet: fix the use of ZERO_PAGE in nvme_execute_identify_ns_nvm()

[Nilay Shroff <nilay@linux.ibm.com>]

Sorry but I forgot to add the reported-by tag.

Reported-by: Yi Zhang <yi.zhang@redhat.com>

On 11/22/24 14:20, Nilay Shroff wrote:
> The nvme_execute_identify_ns_nvm function uses ZERO_PAGE
> for copying SG list with all zeros. As ZERO_PAGE would not
> necessarily return the virtual-address of the zero page, we
> need to first convert the page address to kernel virtual-
> address and then use it as source address for copying the
> data to SG list with all zeros.
> 
> Using return address of ZERO_PAGE(0) as source address for
> copying data to SG list would fill the target buffer with
> random value and causes the undesired side effect. This patch
> implements the fix ensuring that we use virtual-address of the
> zero page for copying all zeros to the SG list buffers.
> 
> Link: https://lore.kernel.org/all/CAHj4cs8OVyxmn4XTvA=y4uQ3qWpdw-x3M3FSUYr-KpE-nhaFEA@mail.gmail.com/
> Fixes: 64a51080eaba ("nvmet: implement id ns for nvm command set")
> [nilay: Use page_to_virt() for converting ZERO_PAGE address to
>         virtual-address as suggested by Maurizio Lombardi]
> Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
> ---
>  drivers/nvme/target/admin-cmd.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
> index 934b401fbc2f..a2b0444f28ab 100644
> --- a/drivers/nvme/target/admin-cmd.c
> +++ b/drivers/nvme/target/admin-cmd.c
> @@ -901,12 +901,14 @@ static void nvmet_execute_identify_ctrl_nvm(struct nvmet_req *req)
>  static void nvme_execute_identify_ns_nvm(struct nvmet_req *req)
>  {
>  	u16 status;
> +	void *zero_buf;
>  
>  	status = nvmet_req_find_ns(req);
>  	if (status)
>  		goto out;
>  
> -	status = nvmet_copy_to_sgl(req, 0, ZERO_PAGE(0),
> +	zero_buf = page_to_virt(ZERO_PAGE(0));
> +	status = nvmet_copy_to_sgl(req, 0, zero_buf,
>  				   NVME_IDENTIFY_DATA_SIZE);
>  out:
>  	nvmet_req_complete(req, status);