1. 04 Jul, 2024 39 commits
  2. 03 Jul, 2024 1 commit
    • Florian Westphal's avatar
      netfilter: nf_tables: unconditionally flush pending work before notifier · 9f6958ba
      Florian Westphal authored
      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 e169285f ("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: 2c9f0293 ("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=4fd66a69358fc15ae2adSigned-off-by: default avatarFlorian Westphal <fw@strlen.de>
      Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
      9f6958ba