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author | Florian Westphal <fw@strlen.de> | 2024-07-02 17:08:14 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-07-11 13:49:13 +0300 |
commit | 55a40406aac555defe9bdd0adec9508116ce7cb1 (patch) | |
tree | adca953ff2d5764f2e803a627cf14436e9ebba7f | |
parent | 7692c9b6baacdee378435f58f19baf0eb69e4155 (diff) | |
download | linux-55a40406aac555defe9bdd0adec9508116ce7cb1.tar.xz |
netfilter: nf_tables: unconditionally flush pending work before notifier
[ Upstream commit 9f6958ba2e902f9820c594869bd710ba74b7c4c0 ]
syzbot reports:
KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831
KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530
KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597
Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45
[..]
Workqueue: events nf_tables_trans_destroy_work
Call Trace:
nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline]
nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline]
nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597
Problem is that the notifier does a conditional flush, but its possible
that the table-to-be-removed is still referenced by transactions being
processed by the worker, so we need to flush unconditionally.
We could make the flush_work depend on whether we found a table to delete
in nf-next to avoid the flush for most cases.
AFAICS this problem is only exposed in nf-next, with
commit e169285f8c56 ("netfilter: nf_tables: do not store nft_ctx in transaction objects"),
with this commit applied there is an unconditional fetch of
table->family which is whats triggering the above splat.
Fixes: 2c9f0293280e ("netfilter: nf_tables: flush pending destroy work before netlink notifier")
Reported-and-tested-by: syzbot+4fd66a69358fc15ae2ad@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4fd66a69358fc15ae2ad
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | net/netfilter/nf_tables_api.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 7547f7b86939..dd044a47c872 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -11291,8 +11291,7 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, gc_seq = nft_gc_seq_begin(nft_net); - if (!list_empty(&nf_tables_destroy_list)) - nf_tables_trans_destroy_flush_work(); + nf_tables_trans_destroy_flush_work(); again: list_for_each_entry(table, &nft_net->tables, list) { if (nft_table_has_owner(table) && |