[PATCH v2] staging: android: Replace strcpy with strlcpy

[PATCH v2] staging: android: Replace strcpy with strlcpy

[simran singhal]

Replace strcpy with strlcpy as strcpy does not check for buffer
overflow.
This is found using Flawfinder.

Signed-off-by: simran singhal <singhalsimran0@gmail.com>
---

 v2:
   -Correcting the place of the parenthesis
 
 drivers/staging/android/ashmem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 7cbad0d..eb2f4ef 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -548,7 +548,8 @@ static int set_name(struct ashmem_area *asma, void __user *name)
 	if (unlikely(asma->file))
 		ret = -EINVAL;
 	else
-		strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
+		strlcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name,
+			sizeof(asma->name + ASHMEM_NAME_PREFIX_LEN));
 
 	mutex_unlock(&ashmem_mutex);
 	return ret;
-- 
2.7.4

Re: [Outreachy kernel] [PATCH v2] staging: android: Replace strcpy with strlcpy

[Julia Lawall]

On Sun, 12 Mar 2017, simran singhal wrote:

> Replace strcpy with strlcpy as strcpy does not check for buffer
> overflow.
> This is found using Flawfinder.
>
> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
> ---
>
>  v2:
>    -Correcting the place of the parenthesis
>
>  drivers/staging/android/ashmem.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
> index 7cbad0d..eb2f4ef 100644
> --- a/drivers/staging/android/ashmem.c
> +++ b/drivers/staging/android/ashmem.c
> @@ -548,7 +548,8 @@ static int set_name(struct ashmem_area *asma, void __user *name)
>  	if (unlikely(asma->file))
>  		ret = -EINVAL;
>  	else
> -		strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
> +		strlcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name,
> +			sizeof(asma->name + ASHMEM_NAME_PREFIX_LEN));

This appears to be the old patch.

Actually, looking closer, I don't think this is right at all.  There seems
to be a goal of leaving some space at the beginning of asma->name.  So the
amount of space available for local_name would be computed using a
subtraction, not an addition.

julia

>
>  	mutex_unlock(&ashmem_mutex);
>  	return ret;
> --
> 2.7.4
>
> --
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Re: [Outreachy kernel] [PATCH v2] staging: android: Replace strcpy with strlcpy

[SIMRAN SINGHAL]

On Sun, Mar 12, 2017 at 2:53 AM, Julia Lawall <julia.lawall@lip6.fr> wrote:
>
>
> On Sun, 12 Mar 2017, simran singhal wrote:
>
>> Replace strcpy with strlcpy as strcpy does not check for buffer
>> overflow.
>> This is found using Flawfinder.
>>
>> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
>> ---
>>
>>  v2:
>>    -Correcting the place of the parenthesis
>>
>>  drivers/staging/android/ashmem.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
>> index 7cbad0d..eb2f4ef 100644
>> --- a/drivers/staging/android/ashmem.c
>> +++ b/drivers/staging/android/ashmem.c
>> @@ -548,7 +548,8 @@ static int set_name(struct ashmem_area *asma, void __user *name)
>>       if (unlikely(asma->file))
>>               ret = -EINVAL;
>>       else
>> -             strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
>> +             strlcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name,
>> +                     sizeof(asma->name + ASHMEM_NAME_PREFIX_LEN));
>
> This appears to be the old patch.
>
> Actually, looking closer, I don't think this is right at all.  There seems
> to be a goal of leaving some space at the beginning of asma->name.  So the
> amount of space available for local_name would be computed using a
> subtraction, not an addition.
>
Julia, By mistake I sent the wrong patch.
And I am not getting you want to mention which space.

> julia
>
>>
>>       mutex_unlock(&ashmem_mutex);
>>       return ret;
>> --
>> 2.7.4
>>
>> --
>> You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com.
>> To post to this group, send email to outreachy-kernel@googlegroups.com.
>> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170311211725.GA12884%40singhal-Inspiron-5558.
>> For more options, visit https://groups.google.com/d/optout.
>>

Re: [Outreachy kernel] [PATCH v2] staging: android: Replace strcpy with strlcpy

[Julia Lawall]

On Sun, 12 Mar 2017, SIMRAN SINGHAL wrote:

> On Sun, Mar 12, 2017 at 2:53 AM, Julia Lawall <julia.lawall@lip6.fr> wrote:
> >
> >
> > On Sun, 12 Mar 2017, simran singhal wrote:
> >
> >> Replace strcpy with strlcpy as strcpy does not check for buffer
> >> overflow.
> >> This is found using Flawfinder.
> >>
> >> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
> >> ---
> >>
> >>  v2:
> >>    -Correcting the place of the parenthesis
> >>
> >>  drivers/staging/android/ashmem.c | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
> >> index 7cbad0d..eb2f4ef 100644
> >> --- a/drivers/staging/android/ashmem.c
> >> +++ b/drivers/staging/android/ashmem.c
> >> @@ -548,7 +548,8 @@ static int set_name(struct ashmem_area *asma, void __user *name)
> >>       if (unlikely(asma->file))
> >>               ret = -EINVAL;
> >>       else
> >> -             strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
> >> +             strlcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name,
> >> +                     sizeof(asma->name + ASHMEM_NAME_PREFIX_LEN));
> >
> > This appears to be the old patch.
> >
> > Actually, looking closer, I don't think this is right at all.  There seems
> > to be a goal of leaving some space at the beginning of asma->name.  So the
> > amount of space available for local_name would be computed using a
> > subtraction, not an addition.
> >
> Julia, By mistake I sent the wrong patch.
> And I am not getting you want to mention which space.

The following is the whole asma->name array.  The | in the middle is the
offset ASHMEM_NAME_PREFIX_LEN.  The xxx characters are in the
ASHMEM_NAME_PREFIX_LEN region.  The space for local_name is only the part
indicates with the ys.  This space is smaller than the size of asma->name.
In your calculation, you are allowing it to be larger.  You will
potentially overflow the buffer by 2 * ASHMEM_NAME_PREFIX_LEN.

     --------------------------
    |xxxxxxx|yyyyyyyyyyyyyyyyyy|
     --------------------------

julia