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Dan Carpenter's smatch tests report that the "vid" variable, populated by sja1105_vlan_rcv when an skb is received by the tagger that has a VLAN ID which cannot be decoded by tag_8021q, may be uninitialized when used here: if (source_port == -1 || switch_id == -1) skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid); The sja1105 driver, by construction, sets up the switch in a way that all data plane packets sent towards the CPU port are VLAN-tagged. So it is practically impossible, in a functional system, for a packet to be processed by sja1110_rcv() which is not a control packet and does not have a VLAN header either. However, it would be nice if the sja1105 tagging driver could consistently do something valid, for example fail, even if presented with packets that do not hold valid sja1105 tags. Currently it is a bit hard to argue that it does that, given the fact that a data plane packet with no VLAN tag will trigger a call to dsa_find_designated_bridge_port_by_vid with a vid argument that is an uninitialized stack variable. To fix this, we can initialize the u16 vid variable with 0, a value that can never be a bridge VLAN, so dsa_find_designated_bridge_port_by_vid will always return a NULL skb->dev. Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Link: https://lore.kernel.org/r/20210802195137.303625-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 Restructured Text 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.