From: Alan Stern <stern@rowland.harvard.edu>
To: trix@redhat.com
Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
usb-storage@lists.one-eyed-alien.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: storage: initialize variable
Date: Sat, 22 Aug 2020 20:49:03 -0400 [thread overview]
Message-ID: <20200823004903.GB292576@rowland.harvard.edu> (raw)
In-Reply-To: <20200822211839.5117-1-trix@redhat.com>
On Sat, Aug 22, 2020 at 02:18:39PM -0700, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis reports this representative problem
>
> transport.c:495:15: warning: Assigned value is garbage or
> undefined
> length_left -= partial;
> ^ ~~~~~~~
> partial is set only when usb_stor_bulk_transfer_sglist()
> is successful.
>
> So initialize to partial to 0.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
> drivers/usb/storage/transport.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
> index 238a8088e17f..ce920851b1f2 100644
> --- a/drivers/usb/storage/transport.c
> +++ b/drivers/usb/storage/transport.c
> @@ -461,7 +461,7 @@ static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
> int usb_stor_bulk_srb(struct us_data* us, unsigned int pipe,
> struct scsi_cmnd* srb)
> {
> - unsigned int partial;
> + unsigned int partial = 0;
> int result = usb_stor_bulk_transfer_sglist(us, pipe, scsi_sglist(srb),
> scsi_sg_count(srb), scsi_bufflen(srb),
> &partial);
> @@ -484,7 +484,7 @@ int usb_stor_bulk_transfer_sg(struct us_data* us, unsigned int pipe,
> void *buf, unsigned int length_left, int use_sg, int *residual)
> {
> int result;
> - unsigned int partial;
> + unsigned int partial = 0;
>
> /* are we scatter-gathering? */
> if (use_sg) {
Yes, this is a bug. But the right way to fix it is to change
usb_stor_bulk_transfer_sglist(): Make it store 0 to *act_len at the
start.
That way you change only one localized piece of code, instead of
changing multiple callers and leaving a possibility of more errors being
added in the future.
Alan Stern
next prev parent reply other threads:[~2020-08-23 0:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-22 21:18 [PATCH] usb: storage: initialize variable trix
2020-08-23 0:49 ` Alan Stern [this message]
2020-08-24 13:13 ` Tom Rix
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200823004903.GB292576@rowland.harvard.edu \
--to=stern@rowland.harvard.edu \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=trix@redhat.com \
--cc=usb-storage@lists.one-eyed-alien.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox