Jakub Kicinski 964417a5d4 tools: ynl: c: correct reverse decode of empty attrs
netlink reports which attribute was incorrect by sending back
an attribute offset. Offset points to the address of struct nlattr,
but to interpret the type we also need the nesting path.
Attribute IDs have different meaning in different nests
of the same message.

Correct the condition for "is the offset within current attribute".
ynl_attr_data_len() does not include the attribute header,
so the end offset was off by 4 bytes.

This means that we'd always skip over flags and empty nests.

The devmem tests, for example, issues an invalid request with
empty queue nests, resulting in the following error:

  YNL failed: Kernel error: missing attribute: .queues.ifindex

The message is incorrect, "queues" nest does not have an "ifindex"
attribute defined. With this fix we decend correctly into the nest:

  YNL failed: Kernel error: missing attribute: .queues.id

Fixes: 86878f14d7 ("tools: ynl: user space helpers")
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250124012130.1121227-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-01-27 14:30:23 -08:00
2024-09-01 20:43:24 -07:00
2022-09-28 09:02:20 +02:00
…
…
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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