linux-kernel - Re: [PATCH] smack: Fix a memory leak in smack_add

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Date:   Fri, 21 Dec 2018 16:42:19 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Casey Schaufler <casey@...aufler-ca.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] smack: Fix a memory leak in smack_add_opt()

On Fri, Dec 21, 2018 at 04:36:54PM +0000, Al Viro wrote:
> On Fri, Dec 21, 2018 at 12:09:58PM +0300, Dan Carpenter wrote:
> > The function is leaking "opts" on the error paths.
> > 
> > Fixes: 90e3b564ab93 ("smack: take the guts of smack_parse_opts_str() into a new helper")
> > Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> 
> D'oh...  Applied, thanks for spotting that braino.

On the other hand, it's easier to do it this way - the caller will free the damn thing
on error, anyway:

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 11da1e2531c8..cf0c0380e5dd 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -608,6 +608,7 @@ static int smack_add_opt(int token, const char *s, void **mnt_opts)
 		opts = kzalloc(sizeof(struct smack_mnt_opts), GFP_KERNEL);
 		if (!opts)
 			return -ENOMEM;
+		*mnt_opts = opts;
 	}
 	if (!s)
 		return -ENOMEM;
@@ -639,7 +640,6 @@ static int smack_add_opt(int token, const char *s, void **mnt_opts)
 		opts->fstransmute = s;
 		break;
 	}
-	*mnt_opts = opts;
 	return 0;
 
 out_opt_err: