lkml.org 
[lkml]   [2020]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH] tomoyo: Avoid potential null pointer access
From
Date
Hello, Tetsuo

Got it , Thank you for your explanation.

> Hello, Zheng.
>
> Thank you for a patch, but I won't apply this patch.
> Expected behavior is that tomoyo_warn_oom() is called
> if tomoyo_memory_ok() is called with entry == NULL.
>
> Adding __GFP_NOWARN might be OK, but returning without tomoyo_warn_oom() is NG.
>
> On 2020/11/25 21:10, Zheng Zengkai wrote:
>> Calls to kzalloc() should be null-checked in order to avoid
>> any potential failures or unnecessary code execution.
>> Fix this by adding null checks for _entry_ right after allocation.
>>
>> Fixes: 57c2590fb7fd ("TOMOYO: Update profile structure")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
> Nacked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

As your say,  I found the function tomoyo_assign_namespace( )

in security/tomoyo/domain.c has the similar situation,

Can I add __GFP_NOWARN for both and remove the null check for _entry_ in
tomoyo_assign_namespace( )?

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 4bee32bfe16d..bc54d3c8c70a 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -498,7 +498,7 @@ static struct tomoyo_profile *tomoyo_assign_profile
        ptr = ns->profile_ptr[profile];
        if (ptr)
                return ptr;
-       entry = kzalloc(sizeof(*entry), GFP_NOFS);
+       entry = kzalloc(sizeof(*entry), GFP_NOFS | __GFP_NOWARN);
        if (mutex_lock_interruptible(&tomoyo_policy_lock))
                goto out;
        ptr = ns->profile_ptr[profile];
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index dc4ecc0b2038..c6e5cc5cc7cd 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -473,9 +473,7 @@ struct tomoyo_policy_namespace
*tomoyo_assign_namespace(const char *domainname)
                return ptr;
        if (len >= TOMOYO_EXEC_TMPSIZE - 10 ||
!tomoyo_domain_def(domainname))
                return NULL;
-       entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS);
-       if (!entry)
-               return NULL;
+       entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS | __GFP_NOWARN);
        if (mutex_lock_interruptible(&tomoyo_policy_lock))
                goto out;
        ptr = tomoyo_find_namespace(domainname, len);
>> ---
>> security/tomoyo/common.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
>> index 4bee32bfe16d..99b4fafcb100 100644
>> --- a/security/tomoyo/common.c
>> +++ b/security/tomoyo/common.c
>> @@ -499,6 +499,8 @@ static struct tomoyo_profile *tomoyo_assign_profile
>> if (ptr)
>> return ptr;
>> entry = kzalloc(sizeof(*entry), GFP_NOFS);
>> + if (!entry)
>> + return NULL;
>> if (mutex_lock_interruptible(&tomoyo_policy_lock))
>> goto out;
>> ptr = ns->profile_ptr[profile];
>>
> .
>

\
 
 \ /
  Last update: 2020-11-26 07:36    [W:0.081 / U:0.896 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site