2022-11-16 13:23:58

by Lin Ma

Subject: [PATCH v2] nfc/nci: fix race with opening and closing

Previously we leverage NCI_UNREG and the lock inside nci_close_device to
prevent the race condition between opening a device and closing a
device. However, it still has problem because a failed opening command
will erase the NCI_UNREG flag and allow another opening command to
bypass the status checking.

This fix corrects that by making sure the NCI_UNREG is held.

Reported-by: [email protected]
Fixes: 48b71a9e66c2 ("NFC: add NCI_UNREG flag to eliminate the race")
Signed-off-by: Lin Ma <[email protected]>
---
V1 -> V2: should be &= instead of =
net/nfc/nci/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index 6a193cce2a75..76ade5d4f55a 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -542,7 +542,7 @@ static int nci_open_device(struct nci_dev *ndev)
skb_queue_purge(&ndev->tx_q);

ndev->ops->close(ndev);
- ndev->flags = 0;
+ ndev->flags &= BIT(NCI_UNREG);
}

done:
--
2.38.1

2022-11-18 13:00:37

by patchwork-bot+netdevbpf

Subject: Re: [PATCH v2] nfc/nci: fix race with opening and closing

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <[email protected]>:

On Wed, 16 Nov 2022 21:02:49 +0800 you wrote:
> Previously we leverage NCI_UNREG and the lock inside nci_close_device to
> prevent the race condition between opening a device and closing a
> device. However, it still has problem because a failed opening command
> will erase the NCI_UNREG flag and allow another opening command to
> bypass the status checking.
>
> This fix corrects that by making sure the NCI_UNREG is held.
>
> [...]

Here is the summary with links:
- [v2] nfc/nci: fix race with opening and closing
https://git.kernel.org/netdev/net/c/0ad6bded175e

You are awesome, thank you!
--
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