linux-kernel - Re: [PATCH] smb: client: Fix a double lock bug in smb2

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Date: Thu, 1 Feb 2024 12:03:43 -0600
From: Steve French <smfrench@...il.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Shyam Prasad N <sprasad@...rosoft.com>, Steve French <sfrench@...ba.org>, 
	Paulo Alcantara <pc@...guebit.com>, Ronnie Sahlberg <ronniesahlberg@...il.com>, Tom Talpey <tom@...pey.com>, 
	linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] smb: client: Fix a double lock bug in smb2_reconnect()

This (and a loosely related problem   were already fixed in an updated
version of that patch (updated in cifs-2.6.git for-next yesterday);
https://git.samba.org/?p=sfrench/cifs-2.6.git;a=commit;h=ee36a3b345c433a846effcdcfba437c2298eeda5


On Thu, Feb 1, 2024 at 6:19 AM Dan Carpenter <dan.carpenter@...aro.org> wrote:
>
> This goto will try to lock spin_lock(&ses->ses_lock) twice which will
> lead to a deadlock.
>
> Fixes: 17525952fa83 ("cifs: make sure that channel scaling is done only once")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>  fs/smb/client/smb2pdu.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
> index 2837fc4465a7..dcd3f6f08c7f 100644
> --- a/fs/smb/client/smb2pdu.c
> +++ b/fs/smb/client/smb2pdu.c
> @@ -401,7 +401,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
>
>         spin_lock(&ses->ses_lock);
>         if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS)
> -               goto skip_add_channels;
> +               goto skip_add_channels_locked;
>         ses->flags |= CIFS_SES_FLAG_SCALE_CHANNELS;
>         spin_unlock(&ses->ses_lock);
>
> @@ -448,6 +448,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
>
>  skip_add_channels:
>         spin_lock(&ses->ses_lock);
> +skip_add_channels_locked:
>         ses->flags &= ~CIFS_SES_FLAG_SCALE_CHANNELS;
>         spin_unlock(&ses->ses_lock);
>
> --
> 2.43.0
>
>


-- 
Thanks,

Steve