linux-kernel - Re: [PATCH] cifs: set length when cifs_copy_pages_to

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Message-ID: <CAKwvOdmPZXiMZRKyMfZVMmw-95XVocSZn3VVi3yJh0Bx1ONbJQ@mail.gmail.com>
Date:   Fri, 27 May 2022 12:32:32 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Steve French <stfrench@...rosoft.com>
Cc:     nathan@...nel.org, dhowells@...hat.com, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Tom Rix <trix@...hat.com>, sfrench@...ba.org
Subject: Re: [PATCH] cifs: set length when cifs_copy_pages_to_iter is successful

+ Steve's @microsoft.com email addr.

On Thu, May 26, 2022 at 7:02 AM Tom Rix <trix@...hat.com> wrote:
>
> clang build fails with
> fs/cifs/smb2ops.c:4984:7: error: variable 'length' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>   if (rdata->result != 0) {
>       ^~~~~~~~~~~~~~~~~~
>
> handle_read_data() returns the number of bytes handled by setting the length variable.
> This only happens in the copy_to_iter() branch, it needs to also happen in the
> cifs_copy_pages_to_iter() branch.  When cifs_copy_pages_to_iter() is successful,
> its parameter data_len is how many bytes were handled, so set length to data_len.
>
> Fixes: 67fd8cff2b0f ("cifs: Change the I/O paths to use an iterator rather than a page list")
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  fs/cifs/smb2ops.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index 3630e132781f..bfad482ec186 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -4988,7 +4988,7 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
>                                 dequeue_mid(mid, rdata->result);
>                         return 0;
>                 }
> -               rdata->got_bytes = pages_len;
> +               length = rdata->got_bytes = pages_len;
>
>         } else if (buf_len >= data_offset + data_len) {
>                 /* read response payload is in buf */
> --
> 2.27.0
>


-- 
Thanks,
~Nick Desaulniers