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Message-Id: <20231213213735.434249-1-thinker.li@gmail.com>
Date: Wed, 13 Dec 2023 13:37:33 -0800
From: thinker.li@...il.com
To: netdev@...r.kernel.org,
martin.lau@...ux.dev,
kernel-team@...a.com,
davem@...emloft.net,
kuba@...nel.org,
pabeni@...hat.com,
dsahern@...nel.org,
edumazet@...gle.com
Cc: sinquersw@...il.com,
kuifeng@...a.com,
Kui-Feng Lee <thinker.li@...il.com>
Subject: [PATCH net-next v3 0/2] Fix dangling pointer at f6i->gc_link.
From: Kui-Feng Lee <thinker.li@...il.com>
According to a report [1], f6i->gc_link may point to a free block
causing use-after-free. According the stacktraces in the report, it is
very likely that a f6i was added to the GC list after being removed
from the tree of a fib6_table. The reason this can happen is the
current implementation determines if a f6i is on a tree in a wrong
way. It believes a f6i is on a tree if f6i->fib6_table is not NULL.
However, f6i->fib6_table is not reset when f6i is removed from a tree.
The new solution is to check if f6i->fib6_node is not NULL as well.
f6i->fib6_node is set/or reset when the f6i is added/or removed from
from a tree. It can be used to determines if a f6i is on a tree
reliably.
The other change is to determine if a f6i is on a GC list. The
current implementation relies on RTF_EXPIRES on fib6_flags. It needs
to consider if a f6i is on a tree as well. The new solution is
checking hlist_unhashed() on f6i->gc_link, a clear evidence, instead.
[1] https://lore.kernel.org/all/20231205173250.2982846-1-edumazet@google.com/
---
Major changes from v2:
- Ensure dependencies of checks in the test cases.
Major changes from v1:
- Split fib6_set_expires_locked() and fib6_clean_expires_locked()
- Use hlist_unhashed() on gc_link instead of checking RTF_EXPIRES to
determine if a f6i is on a GC list.
- Add tests on toggling routes between permanent and temporary.
v2: https://lore.kernel.org/all/20231208194523.312416-1-thinker.li@gmail.com/
v1: https://lore.kernel.org/all/20231207221627.746324-1-thinker.li@gmail.com/
Kui-Feng Lee (2):
net/ipv6: insert a f6i to a GC list only if the f6i is in a fib6_table
tree.
selftests: fib_tests: Add tests for toggling between w/ and w/o
expires.
include/net/ip6_fib.h | 46 +++++++++----
net/ipv6/route.c | 6 +-
tools/testing/selftests/net/fib_tests.sh | 82 +++++++++++++++++++++++-
3 files changed, 118 insertions(+), 16 deletions(-)
--
2.34.1
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