net: add networking namespace refcount tracker

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We have 100+ syzbot reports about netns being dismantled too soon,
still unresolved as of today.

We think a missing get_net() or an extra put_net() is the root cause.

In order to find the bug(s), and be able to spot future ones,
this patch adds CONFIG_NET_NS_REFCNT_TRACKER and new helpers
to precisely pair all put_net() with corresponding get_net().

To use these helpers, each data structure owning a refcount
should also use a "netns_tracker" to pair the get and put.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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This commit is contained in:

Eric Dumazet 2021-12-09 23:44:21 -08:00 • committed by Jakub Kicinski

parent e5d75fc20b

commit 9ba74e6c9e

5 changed files with 65 additions and 8 deletions

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9

include/linux/netdevice.h

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34

include/net/net_namespace.h

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18

include/net/net_trackers.h

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9

net/Kconfig.debug

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3

net/core/net_namespace.c

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