linux-kernel - Re: [PATCH V6 4/4] audit: avoid double copying the audit

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Message-ID: <9338092.i1kyKho6FJ@sifl>
Date:	Thu, 16 Jul 2015 21:56:12 -0400
From:	Paul Moore <pmoore@...hat.com>
To:	Richard Guy Briggs <rgb@...hat.com>
Cc:	linux-audit@...hat.com, linux-kernel@...r.kernel.org,
	sgrubb@...hat.com, eparis@...hat.com, pmoody@...gle.com
Subject: Re: [PATCH V6 4/4] audit: avoid double copying the audit_exe path string

On Tuesday, July 14, 2015 11:50:26 AM Richard Guy Briggs wrote:
> Make this interface consistent with watch and filter key, avoiding the extra
> string copy and simply consume the new string pointer.
> 
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> ---
>  kernel/audit_exe.c      |    8 ++++++--
>  kernel/audit_fsnotify.c |    9 +--------
>  kernel/auditfilter.c    |    2 +-
>  3 files changed, 8 insertions(+), 11 deletions(-)

Merge this patch too, there is no reason why these needs to be its own patch.

> diff --git a/kernel/audit_exe.c b/kernel/audit_exe.c
> index 75ad4f2..09e4eb4 100644
> --- a/kernel/audit_exe.c
> +++ b/kernel/audit_exe.c
> @@ -27,11 +27,15 @@ int audit_dupe_exe(struct audit_krule *new, struct
> audit_krule *old) struct audit_fsnotify_mark *audit_mark;
>  	char *pathname;
> 
> -	pathname = audit_mark_path(old->exe);
> +	pathname = kstrdup(audit_mark_path(old->exe), GFP_KERNEL);
> +	if (!pathname)
> +		return -ENOMEM;
> 
>  	audit_mark = audit_alloc_mark(new, pathname, strlen(pathname));
> -	if (IS_ERR(audit_mark))
> +	if (IS_ERR(audit_mark)) {
> +		kfree(pathname);
>  		return PTR_ERR(audit_mark);
> +	}
>  	new->exe = audit_mark;
> 
>  	return 0;
> diff --git a/kernel/audit_fsnotify.c b/kernel/audit_fsnotify.c
> index a4e7b16..e57e08a 100644
> --- a/kernel/audit_fsnotify.c
> +++ b/kernel/audit_fsnotify.c
> @@ -94,7 +94,6 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct
> audit_krule *krule, char *pa struct dentry *dentry;
>  	struct inode *inode;
>  	unsigned long ino;
> -	char *local_pathname;
>  	dev_t dev;
>  	int ret;
> 
> @@ -115,21 +114,15 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct
> audit_krule *krule, char *pa ino = dentry->d_inode->i_ino;
>  	}
> 
> -	audit_mark = ERR_PTR(-ENOMEM);
> -	local_pathname = kstrdup(pathname, GFP_KERNEL);
> -	if (!local_pathname)
> -		goto out;
> -
>  	audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
>  	if (unlikely(!audit_mark)) {
> -		kfree(local_pathname);
>  		audit_mark = ERR_PTR(-ENOMEM);
>  		goto out;
>  	}
> 
>  	fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_free_mark);
>  	audit_mark->mark.mask = AUDIT_FS_EVENTS;
> -	audit_mark->path = local_pathname;
> +	audit_mark->path = pathname;
>  	audit_mark->ino = ino;
>  	audit_mark->dev = dev;
>  	audit_mark->rule = krule;
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index f65c97f..f46ed69 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -559,8 +559,8 @@ static struct audit_entry *audit_data_to_entry(struct
> audit_rule_data *data, entry->rule.buflen += f->val;
> 
>  			audit_mark = audit_alloc_mark(&entry->rule, str, f->val);
> -			kfree(str);
>  			if (IS_ERR(audit_mark)) {
> +				kfree(str);
>  				err = PTR_ERR(audit_mark);
>  				goto exit_free;
>  			}

-- 
paul moore
security @ redhat

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