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fda6c89fe3
lianhui reports that when MPLS fails to register the sysctl table
under new location (during device rename) the old pointers won't
get overwritten and may be freed again (double free).
Handle this gracefully. The best option would be unregistering
the MPLS from the device completely on failure, but unfortunately
mpls_ifdown() can fail. So failing fully is also unreliable.
Another option is to register the new table first then only
remove old one if the new one succeeds. That requires more
code, changes order of notifications and two tables may be
visible at the same time.
sysctl point is not used in the rest of the code - set to NULL
on failures and skip unregister if already NULL.
Reported-by: lianhui tang <bluetlh@gmail.com>
Fixes: 0fae3bf018d9 ("mpls: handle device renames for per-device sysctls")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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.