Re: IPA_STATUS_SIZE, commit b8dc7d0eea5a7709bb534f1b3ca70d2d7de0b42c

From: Alex Elder
Date: Fri May 26 2023 - 08:30:04 EST

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
     difficult to represent cleanly.  As a small step toward
     it as a parsed block of data, use a constant to define its
     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) =
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.


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://
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
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>

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.


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

drivers/net/ipa/ipa_endpoint.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/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,