lkml.org 
[lkml]   [2020]   [Dec]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.9 72/75] netfilter: nf_tables: avoid false-postive lockdep splat
Date
From: Florian Westphal <fw@strlen.de>

commit c0700dfa2cae44c033ed97dade8a2679c7d22a9d upstream.

There are reports wrt lockdep splat in nftables, e.g.:
------------[ cut here ]------------
WARNING: CPU: 2 PID: 31416 at net/netfilter/nf_tables_api.c:622
lockdep_nfnl_nft_mutex_not_held+0x28/0x38 [nf_tables]
...

These are caused by an earlier, unrelated bug such as a n ABBA deadlock
in a different subsystem.
In such an event, lockdep is disabled and lockdep_is_held returns true
unconditionally. This then causes the WARN() in nf_tables.

Make the WARN conditional on lockdep still active to avoid this.

Fixes: f102d66b335a417 ("netfilter: nf_tables: use dedicated mutex to guard transactions")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Link: https://lore.kernel.org/linux-kselftest/CA+G9fYvFUpODs+NkSYcnwKnXm62tmP=ksLeBPmB+KFrB2rvCtQ@mail.gmail.com/
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/netfilter/nf_tables_api.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -619,7 +619,8 @@ static int nft_request_module(struct net
static void lockdep_nfnl_nft_mutex_not_held(void)
{
#ifdef CONFIG_PROVE_LOCKING
- WARN_ON_ONCE(lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES));
+ if (debug_locks)
+ WARN_ON_ONCE(lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES));
#endif
}


\
 
 \ /
  Last update: 2020-12-10 15:51    [W:0.495 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site