Re: IPA_STATUS_SIZE, commit b8dc7d0eea5a7709bb534f1b3ca70d2d7de0b42c

[Alex Elder]

On 5/18/23 5:12 PM, Bert Karwatzki wrote:
> Am Mittwoch, dem 17.05.2023 um 16:35 -0500 schrieb Alex Elder:
> > On 5/12/23 8:04 AM, Bert Karwatzki wrote:
> > > commit b8dc7d0eea5a7709bb534f1b3ca70d2d7de0b42c
> > > Author: Alex Elder <elder@xxxxxxxxxx>
> > > Date:   Wed Jan 25 14:45:39 2023 -0600
> > >
> > >       net: ipa: stop using sizeof(status)
> > >       
> > >       The IPA packet status structure changes in IPA v5.0 in ways
> > > that
> > > are
> > >       difficult to represent cleanly.  As a small step toward
> > > redefining
> > >       it as a parsed block of data, use a constant to define its
> > > size,
> > >       rather than the size of the IPA status structure type.
> > >       
> > >       Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
> > >       Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> > >
> > > introduced the IPA_STATUS_SIZE constant as a replacent for
> > > sizeof(struct ipa_status). IPA_STATUS_SIZE is defined as
> > > sizeof(__le32[4]), but sizeof(struct ipa_status) =
> > > sizeof(__le32[8])
> > > and the newly introducded ipa_status_extract operates on 8 __le32
> > > words, so I wondered if IPA_STATUS_SIZE is correct.
> >
> > You are right to wonder about this.  I think you have identified
> > a bug.  It is a bug that most likely almost never matters (because
> > the status size is always proper--and not too small), but it is
> > a bug nevertheless.
> >
> > Would you like to provide a patch to fix this?  Otherwise I can
> > do that, and I'll provide credit to you:
> >
> >       Reported-by: Bert Karwatzki <spasswolf@xxxxxx>
> >
> > Please let me know.  Thanks for inquiring about/reporting this.
> >
> >                                          -Alex
> >
> > > Bert Karwatzki
>
> Here's the patch that addresse the issue (if there's a > in front of
> the first From, that seems to be a quirk of evolution ...)

Your patch looks correct, and again I really appreciate your
finding and fixing it.  Since the ipa_status structure is no
longer defined, I might now suggest just defining the value
as ((size_t)32), but that's not a big deal

To get your patch accepted, please re-send it, taking into
account the following:
- Make sure your patch is based on the upstream "net" branch:
    Remote: git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
    Branch: main
  (For this trivial fix this might not be critical.)
- Update your subject line, something like:
    [PATCH net] net: ipa: use proper value for IPA_STATUS_SIZE
  Be sure to include the "net" part; it indicates that the patch
  is a bug fix and should be back-ported.
- Add a one or two sentence description in the patch header.
  Something like:
    A recent commit introduced the IPA_STATUS_SIZE constant as
    a replacement for sizeof(struct ipa_status).  IPA_STATUS_SIZE
    was defined as sizeof(__le32[4]) (16 bytes), which is incorrect.
    The actual size of that (since removed) structure was 32 bytes,
    or sizeof(__le32[8]).  Correct the incorrect value.
- At the end,  add your sign-off:
    Signed-off-by: Bert Karwatzki <spasswolf@xxxxxx>
- And on the line directly above your sign-off, add a "Fixed"
  tag to indicate where the bug got introduced:
    Fixes: b8dc7d0eea5a ("net: ipa: stop using sizeof(status)")
- Address the patch message to the network maintainers, who
  can incorporate it into their current "net" branch, and
  arrange for the fix to be back-ported to older stable
  branches.
    David S. Miller <davem@xxxxxxxxxxxxx>
    Eric Dumazet <edumazet@xxxxxxxxxx>
    Jakub Kicinski <kuba@xxxxxxxxxx>
    Paolo Abeni <pabeni@xxxxxxxxxx>
- Carbon-copy me, and some mailing lists:
    Alex Elder <elder@xxxxxxxxxx>
    netdev@xxxxxxxxxxxxxxx
    linux-arm-msm@xxxxxxxxxxxxxxx
    linux-kernel@xxxxxxxxxxxxxxx

Once I receive the updated patch (assuming everything is
order), I will add my "Reviewed-by" and the network
maintainers can merge it and begin the process to get it
back-ported to earlier releases.

If you like, I can do all of this on your behalf.  Provided
you give me your sign-off (i.e., just send me a message that
includes "Signed-off-by: Bert Karwatzki <spasswolf@xxxxxx>")
I can send it and will credit you for identifying the bug
and sending the fix.

					-Alex


>  From 583f35b3d91f048d413fc4f6a3b9237fc9d7efb2 Mon Sep 17 00:00:00 2001
> From: Bert Karwatzki <spasswolf@xxxxxx>
> Date: Fri, 19 May 2023 00:02:55 +0200
> Subject: [PATCH] Make IPA_STATUS_SIZE equal to the size of the remove
> struct
>   ipa_status.
>
> ---
>   drivers/net/ipa/ipa_endpoint.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ipa/ipa_endpoint.c
> b/drivers/net/ipa/ipa_endpoint.c
> index 2ee80ed140b7..afa1d56d9095 100644
> --- a/drivers/net/ipa/ipa_endpoint.c
> +++ b/drivers/net/ipa/ipa_endpoint.c
> @@ -119,7 +119,7 @@ enum ipa_status_field_id {
>   };
>   
>   /* Size in bytes of an IPA packet status structure */
> -#define IPA_STATUS_SIZE			sizeof(__le32[4])
> +#define IPA_STATUS_SIZE			sizeof(__le32[8])
>   
>   /* IPA status structure decoder; looks up field values for a structure
> */
>   static u32 ipa_status_extract(struct ipa *ipa, const void *data,