307201a3d4
Davide Caratti says:
====================
net/sched: cls_u32: fix refcount leak
a refcount leak in the error path of u32_change() has been recently
introduced. It can be observed with the following commands:
[root@f31 ~]# tc filter replace dev eth0 ingress protocol ip prio 97 \
> u32 match ip src 127.0.0.1/32 indev notexist20 flowid 1:1 action drop
RTNETLINK answers: Invalid argument
We have an error talking to the kernel
[root@f31 ~]# tc filter replace dev eth0 ingress protocol ip prio 98 \
> handle 42:42 u32 divisor 256
Error: cls_u32: Divisor can only be used on a hash table.
We have an error talking to the kernel
[root@f31 ~]# tc filter replace dev eth0 ingress protocol ip prio 99 \
> u32 ht 47:47
Error: cls_u32: Specified hash table not found.
We have an error talking to the kernel
they all legitimately return -EINVAL; however, they leave semi-configured
filters at eth0 tc ingress:
[root@f31 ~]# tc filter show dev eth0 ingress
filter protocol ip pref 97 u32 chain 0
filter protocol ip pref 97 u32 chain 0 fh 800: ht divisor 1
filter protocol ip pref 98 u32 chain 0
filter protocol ip pref 98 u32 chain 0 fh 801: ht divisor 1
filter protocol ip pref 99 u32 chain 0
filter protocol ip pref 99 u32 chain 0 fh 802: ht divisor 1
With older kernels, filters were unconditionally considered empty (and
thus de-refcounted) on the error path of ->change().
After commit 8b64678e0af8 ("net: sched: refactor tp insert/delete for
concurrent execution"), filters were considered empty when the walk()
function didn't set 'walker.stop' to 1.
Finally, with commit 6676d5e416ee ("net: sched: set dedicated tcf_walker
flag when tp is empty"), tc filters are considered empty unless the walker
function is called with a non-NULL handle. This last change doesn't fit
cls_u32 design, because at least the "root hnode" is (almost) always
non-NULL, as it's allocated in u32_init().
- patch 1/2 is a proposal to restore the original kernel behavior, where
no filter was installed in the error path of u32_change().
- patch 2/2 adds tdc selftests that can be ued to verify the correct
behavior of u32 in the error path of ->change().
====================
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.