linux-kernel - Re: [PATCH] tty: nozomi: Return an error when failing to create the sysfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YqGxjwLHxaXG/646@kroah.com>
Date:   Thu, 9 Jun 2022 10:38:39 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Zheyu Ma <zheyuma97@...il.com>
Cc:     jirislaby@...nel.org, fseidel@...e.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty: nozomi: Return an error when failing to create the
 sysfs

On Thu, Jun 09, 2022 at 04:31:33PM +0800, Zheyu Ma wrote:
> The driver does not handle the error of the creation of sysfs, resulting
> in duplicate file names being created.
> 
> The following log can reveal it:
> 
> [   52.907211] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:05.0/card_type'

How is the same file being created in a normal codepath?

Is the same device being registered twice somehow?

> [   52.907224] Call Trace:
> [   52.907269]  sysfs_add_file_mode_ns+0x23f/0x2b0
> [   52.907281]  sysfs_create_file_ns+0xe9/0x170
> [   52.907321]  nozomi_card_init+0x97f/0x12c0 [nozomi]
> 
> Fix this bug by returning an error when failing to create the sysfs.
> 
> Fixes: 20fd1e3bea55 ("nozomi driver")
> Signed-off-by: Zheyu Ma <zheyuma97@...il.com>
> ---
>  drivers/tty/nozomi.c | 24 ++++++++++++++++++++----
>  1 file changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
> index 0454c78deee6..d0ad1b9898f5 100644
> --- a/drivers/tty/nozomi.c
> +++ b/drivers/tty/nozomi.c
> @@ -1282,14 +1282,26 @@ static ssize_t open_ttys_show(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_RO(open_ttys);
>  
> -static void make_sysfs_files(struct nozomi *dc)
> +static int make_sysfs_files(struct nozomi *dc)
>  {
> -	if (device_create_file(&dc->pdev->dev, &dev_attr_card_type))
> +	int err;
> +
> +	err = device_create_file(&dc->pdev->dev, &dev_attr_card_type);

Drivers shouldn't be calling this function anyway, it's a race
condition.  How about switching this to use the proper device groups
functionality instead which moves all of the handling of the sysfs files
to the driver core so that the driver can not get it wrong?

That should solve the error handling case.  The fact that this is trying
to be created twice is a symptom of a worse problem here.  How are you
duplicating this?

thanks,

greg k-h