linux-kernel - Re: [PATCH] sysfs: Don't leak secdata when a sysfs

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Date:	Wed, 4 Nov 2009 08:09:13 -0600
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Greg Kroah-Hartman <gregkh@...e.de>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, sds@...ho.nsa.gov, jmorris@...ei.org,
	casey@...aufler-ca.com, linux-security-module@...r.kernel.org
Subject: Re: [PATCH] sysfs: Don't leak secdata when a sysfs_dirent is freed.

Quoting Eric W. Biederman (ebiederm@...ssion.com):
> 
> While refreshing my sysfs patches I noticed a leak in the secdata
> implementation.  We don't free the secdata when we free the
> sysfs dirent. 
> 
> This is a bug in 2.6.32-rc5 that we really should close.
> 
> Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>

I'm surprised no kmemleak or anything has found this - but I guess
not many sites hand-set custom selinux contexts on sysfs?

Acked-by: Serge Hallyn <serue@...ibm.com>

> ---
> 
>  fs/sysfs/dir.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
> index 5fad489..e020183 100644
> --- a/fs/sysfs/dir.c
> +++ b/fs/sysfs/dir.c
> @@ -21,6 +21,7 @@
>  #include <linux/completion.h>
>  #include <linux/mutex.h>
>  #include <linux/slab.h>
> +#include <linux/security.h>
>  #include "sysfs.h"
> 
>  DEFINE_MUTEX(sysfs_mutex);
> @@ -285,6 +286,9 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
>  		sysfs_put(sd->s_symlink.target_sd);
>  	if (sysfs_type(sd) & SYSFS_COPY_NAME)
>  		kfree(sd->s_name);
> +	if (sd->s_iattr && sd->s_iattr->ia_secdata)
> +		security_release_secctx(sd->s_iattr->ia_secdata,
> +					sd->s_iattr->ia_secdata_len);
>  	kfree(sd->s_iattr);
>  	sysfs_free_ino(sd->s_ino);
>  	kmem_cache_free(sysfs_dir_cachep, sd);
> -- 
> 1.6.5.2.143.g8cc62
> 
> --
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