[PATCH][next][V2] io_uring: Fix incorrect sizeof operator for copy_from_user call

[PATCH][next][V2] io_uring: Fix incorrect sizeof operator for copy_from_user call

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Static analysis is warning that the sizeof being used is should be
of *data->tags[i] and not data->tags[i]. Although these are the same
size on 64 bit systems it is not a portable assumption to assume
this is true for all cases.  Fix this by using a temporary pointer
tag_slot to make the code a clearer.

Addresses-Coverity: ("Sizeof not portable")
Fixes: d878c81610e1 ("io_uring: hide rsrc tag copy into generic helpers")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
V2: Use temp variable tag_slot, this makes code clearer as suggested by
    Pavel Begunkov.
---
 fs/io_uring.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d665c9419ad3..7538d0878ff5 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7230,8 +7230,10 @@ static int io_rsrc_data_alloc(struct io_ring_ctx *ctx, rsrc_put_fn *do_put,
 	if (utags) {
 		ret = -EFAULT;
 		for (i = 0; i < nr; i++) {
-			if (copy_from_user(io_get_tag_slot(data, i), &utags[i],
-					   sizeof(data->tags[i])))
+			u64 *tag_slot = io_get_tag_slot(data, i);
+
+			if (copy_from_user(tag_slot, &utags[i],
+					   sizeof(*tag_slot)))
 				goto fail;
 		}
 	}
-- 
2.31.1

Re: [PATCH][next][V2] io_uring: Fix incorrect sizeof operator for copy_from_user call

[Pavel Begunkov]

On 6/15/21 2:00 PM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Static analysis is warning that the sizeof being used is should be
> of *data->tags[i] and not data->tags[i]. Although these are the same
> size on 64 bit systems it is not a portable assumption to assume
> this is true for all cases.  Fix this by using a temporary pointer
> tag_slot to make the code a clearer.
> 
> Addresses-Coverity: ("Sizeof not portable")
> Fixes: d878c81610e1 ("io_uring: hide rsrc tag copy into generic helpers")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

> ---
> V2: Use temp variable tag_slot, this makes code clearer as suggested by
>     Pavel Begunkov.
> ---
>  fs/io_uring.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index d665c9419ad3..7538d0878ff5 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -7230,8 +7230,10 @@ static int io_rsrc_data_alloc(struct io_ring_ctx *ctx, rsrc_put_fn *do_put,
>  	if (utags) {
>  		ret = -EFAULT;
>  		for (i = 0; i < nr; i++) {
> -			if (copy_from_user(io_get_tag_slot(data, i), &utags[i],
> -					   sizeof(data->tags[i])))
> +			u64 *tag_slot = io_get_tag_slot(data, i);
> +
> +			if (copy_from_user(tag_slot, &utags[i],
> +					   sizeof(*tag_slot)))
>  				goto fail;
>  		}
>  	}
> 

-- 
Pavel Begunkov

Re: [PATCH][next][V2] io_uring: Fix incorrect sizeof operator for copy_from_user call

[Jens Axboe]

On 6/15/21 7:00 AM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Static analysis is warning that the sizeof being used is should be
> of *data->tags[i] and not data->tags[i]. Although these are the same
> size on 64 bit systems it is not a portable assumption to assume
> this is true for all cases.  Fix this by using a temporary pointer
> tag_slot to make the code a clearer.

Applied, thanks.

-- 
Jens Axboe