[PATCH] security/selinux: fix potential memleak in error branch

[PATCH] security/selinux: fix potential memleak in error branch

[Bernard Zhao]

This patch try to fix potential memleak in error branch.

Signed-off-by: Bernard Zhao <bernard@vivo.com>
---
 security/selinux/hooks.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 62d30c0a30c2..10700720bb74 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -983,6 +983,7 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
 static int selinux_add_opt(int token, const char *s, void **mnt_opts)
 {
 	struct selinux_mnt_opts *opts = *mnt_opts;
+	bool is_alloc_opts = false;
 
 	if (token == Opt_seclabel)	/* eaten and completely ignored */
 		return 0;
@@ -992,9 +993,13 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
 		if (!opts)
 			return -ENOMEM;
 		*mnt_opts = opts;
+		is_alloc_opts = true;
 	}
-	if (!s)
+	if (!s) {
+		if (is_alloc_opts)
+			kfree(opts);
 		return -ENOMEM;
+	}
 	switch (token) {
 	case Opt_context:
 		if (opts->context || opts->defcontext)
@@ -1020,6 +1025,8 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
 	return 0;
 Einval:
 	pr_warn(SEL_MOUNT_FAIL_MSG);
+	if (is_alloc_opts)
+		kfree(opts);
 	return -EINVAL;
 }
 
-- 
2.33.1

Re: [PATCH] security/selinux: fix potential memleak in error branch

[Paul Moore]

On Wed, Dec 1, 2021 at 10:12 PM Bernard Zhao <bernard@vivo.com> wrote:
>
> This patch try to fix potential memleak in error branch.
>
> Signed-off-by: Bernard Zhao <bernard@vivo.com>
> ---
>  security/selinux/hooks.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 62d30c0a30c2..10700720bb74 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -983,6 +983,7 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
>  static int selinux_add_opt(int token, const char *s, void **mnt_opts)
>  {
>         struct selinux_mnt_opts *opts = *mnt_opts;
> +       bool is_alloc_opts = false;
>
>         if (token == Opt_seclabel)      /* eaten and completely ignored */
>                 return 0;
> @@ -992,9 +993,13 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
>                 if (!opts)
>                         return -ENOMEM;
>                 *mnt_opts = opts;
> +               is_alloc_opts = true;
>         }
> -       if (!s)
> +       if (!s) {
> +               if (is_alloc_opts)
> +                       kfree(opts);
>                 return -ENOMEM;
> +       }

Thanks for catching this and submitting a patch, but would it be
simpler to do the "(!s)" check before the "(!opts)" check?

>         switch (token) {
>         case Opt_context:
>                 if (opts->context || opts->defcontext)
> @@ -1020,6 +1025,8 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
>         return 0;
>  Einval:
>         pr_warn(SEL_MOUNT_FAIL_MSG);
> +       if (is_alloc_opts)
> +               kfree(opts);
>         return -EINVAL;
>  }
>
> --
> 2.33.1

-- 
paul moore
www.paul-moore.com

答复: [PATCH] security/selinux: fix potential memleak in error branch

[赵军奎]

-----邮件原件-----
发件人: bernard@vivo.com <bernard@vivo.com> 代表 Paul Moore
发送时间: 2021年12月6日 11:23
收件人: 赵军奎 <bernard@vivo.com>
抄送: Stephen Smalley <stephen.smalley.work@gmail.com>; Eric Paris <eparis@parisplace.org>; selinux@vger.kernel.org; linux-kernel@vger.kernel.org
主题: Re: [PATCH] security/selinux: fix potential memleak in error branch

On Wed, Dec 1, 2021 at 10:12 PM Bernard Zhao <bernard@vivo.com> wrote:
>
> This patch try to fix potential memleak in error branch.
>
> Signed-off-by: Bernard Zhao <bernard@vivo.com>
> ---
>  security/selinux/hooks.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 
> 62d30c0a30c2..10700720bb74 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -983,6 +983,7 @@ static int selinux_sb_clone_mnt_opts(const struct 
> super_block *oldsb,  static int selinux_add_opt(int token, const char 
> *s, void **mnt_opts)  {
>         struct selinux_mnt_opts *opts = *mnt_opts;
> +       bool is_alloc_opts = false;
>
>         if (token == Opt_seclabel)      /* eaten and completely ignored */
>                 return 0;
> @@ -992,9 +993,13 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
>                 if (!opts)
>                         return -ENOMEM;
>                 *mnt_opts = opts;
> +               is_alloc_opts = true;
>         }
> -       if (!s)
> +       if (!s) {
> +               if (is_alloc_opts)
> +                       kfree(opts);
>                 return -ENOMEM;
> +       }

>Thanks for catching this and submitting a patch, but would it be simpler to do the "(!s)" check before the "(!opts)" check?

Hi paul moore：

This seems to be a good idea, thanks for your comments!
I will modify this and resubmit a version of this patch!
Thanks!

BR//Bernard

>         switch (token) {
>         case Opt_context:
>                 if (opts->context || opts->defcontext) @@ -1020,6 
> +1025,8 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
>         return 0;
>  Einval:
>         pr_warn(SEL_MOUNT_FAIL_MSG);
> +       if (is_alloc_opts)
> +               kfree(opts);
>         return -EINVAL;
>  }
>
> --
> 2.33.1

--
paul moore
www.paul-moore.com