linux-kernel - Re: [PATCH -next] selinux: Fix memleak in security_read_state

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Date:   Tue, 14 Jun 2022 21:34:53 +0800
From:   xiujianfeng <xiujianfeng@...wei.com>
To:     Ondrej Mosnacek <omosnace@...hat.com>
CC:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>,
        Christian Göttsche <cgzones@...glemail.com>,
        <michalorzel.eng@...il.com>, Austin Kim <austin.kim@....com>,
        SElinux list <selinux@...r.kernel.org>,
        Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] selinux: Fix memleak in security_read_state_kernel


在 2022/6/14 20:57, Ondrej Mosnacek 写道:
> On Mon, Jun 13, 2022 at 4:02 PM Xiu Jianfeng <xiujianfeng@...wei.com> wrote:
>> In this function, it directly returns the result of __security_read_policy
>> without freeing the allocated memory in *data, cause memory leak issue,
>> so free the memory if __security_read_policy failed.
>>
>> Signed-off-by: Xiu Jianfeng <xiujianfeng@...wei.com>
>> ---
>>   security/selinux/ss/services.c | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
>> index 69b2734311a6..fe5fcf571c56 100644
>> --- a/security/selinux/ss/services.c
>> +++ b/security/selinux/ss/services.c
>> @@ -4048,6 +4048,7 @@ int security_read_policy(struct selinux_state *state,
>>   int security_read_state_kernel(struct selinux_state *state,
>>                                 void **data, size_t *len)
>>   {
>> +       int err;
>>          struct selinux_policy *policy;
>>
>>          policy = rcu_dereference_protected(
>> @@ -4060,5 +4061,11 @@ int security_read_state_kernel(struct selinux_state *state,
>>          if (!*data)
>>                  return -ENOMEM;
>>
>> -       return __security_read_policy(policy, *data, len);
>> +       err = __security_read_policy(policy, *data, len);
>> +       if (err) {
>> +               vfree(*data);
>> +               *data = NULL;
>> +               *len = 0;
>> +       }
>> +       return err;
>>   }
>> --
>> 2.17.1
>>
> security_read_policy() defined a few lines above has the same pattern
> (just with vmalloc_user() in place of vmalloc()). Would you like to
> send another patch to fix that function as well?
No problem, patch already sent.
>