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From: David Ahern <dsahern@gmail.com>
To: Ioana Ciornei <ciorneiioana@gmail.com>,
	Yajun Deng <yajun.deng@linux.dev>
Cc: davem@davemloft.net, kuba@kernel.org, yoshfuji@linux-ipv6.org,
	dsahern@kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-decnet-user@lists.sourceforge.net
Subject: Re: [PATCH] net: convert fib_treeref from int to refcount_t
Date: Mon, 2 Aug 2021 08:36:59 -0600	[thread overview]
Message-ID: <2033809a-1a07-1f5d-7732-f10f6e094f3d@gmail.com> (raw)
In-Reply-To: <20210802133727.bml3be3tpjgld45j@skbuf>

[-- Attachment #1: Type: text/plain, Size: 177 bytes --]

On 8/2/21 7:37 AM, Ioana Ciornei wrote:
> Unfortunately, with this patch applied I get into the following WARNINGs
> when booting over NFS:

Can you test the attached?

Thanks,

[-- Attachment #2: 0001-ipv4-Fix-refcount-warning-for-new-fib_info.patch --]
[-- Type: text/plain, Size: 1680 bytes --]

From ec9d169eb33e6a65db641792821cc6a259ed9362 Mon Sep 17 00:00:00 2001
From: David Ahern <dsahern@kernel.org>
Date: Mon, 2 Aug 2021 08:29:26 -0600
Subject: [PATCH net-next] ipv4: Fix refcount warning for new fib_info

Ioana reported a refcount warning when booting over NFS:

[    5.042532] ------------[ cut here ]------------
[    5.047184] refcount_t: addition on 0; use-after-free.
[    5.052324] WARNING: CPU: 7 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0xa4/0x150
...
[    5.167201] Call trace:
[    5.169635]  refcount_warn_saturate+0xa4/0x150
[    5.174067]  fib_create_info+0xc00/0xc90
[    5.177982]  fib_table_insert+0x8c/0x620
[    5.181893]  fib_magic.isra.0+0x110/0x11c
[    5.185891]  fib_add_ifaddr+0xb8/0x190
[    5.189629]  fib_inetaddr_event+0x8c/0x140

fib_treeref needs to be set after kzalloc. The old code had a ++ which
led to the confusion when the int was replaced by a refcount_t.

Fixes: 79976892f7ea ("net: convert fib_treeref from int to refcount_t")
Signed-off-by: David Ahern <dsahern@kernel.org>
Reported-by: Ioana Ciornei <ciorneiioana@gmail.com>
Cc: Yajun Deng <yajun.deng@linux.dev>
---
 net/ipv4/fib_semantics.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index fa19f4cdf3a4..f29feb7772da 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1551,7 +1551,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 		return ofi;
 	}
 
-	refcount_inc(&fi->fib_treeref);
+	refcount_set(&fi->fib_treeref, 1);
 	refcount_set(&fi->fib_clntref, 1);
 	spin_lock_bh(&fib_info_lock);
 	hlist_add_head(&fi->fib_hash,
-- 
2.24.3 (Apple Git-128)


  reply	other threads:[~2021-08-02 14:37 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29  7:13 Yajun Deng
2021-07-29 14:55 ` David Ahern
2021-07-30 15:30 ` patchwork-bot+netdevbpf
2021-08-02 13:37 ` Ioana Ciornei
2021-08-02 14:36   ` David Ahern [this message]
2021-08-02 14:59     ` Ioana Ciornei
2021-08-03 11:17   ` Fwd: " yajun.deng
2021-08-03 11:24     ` Marek Szyprowski
     [not found] ` <CGME20210803110803eucas1p276a0010caad8fc21a7ea5ca5543294f8@eucas1p2.samsung.com>
2021-08-03 11:08   ` Marek Szyprowski
2021-08-03 14:43     ` David Ahern

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