[dpdk-dev] bus/pci: fix driver name string manipulation
diff mbox

Message ID 20180515100335.13051-1-jerin.jacob@caviumnetworks.com
State Rejected, archived
Delegated to: Thomas Monjalon
Headers show

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Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Jerin Jacob May 15, 2018, 10:03 a.m. UTC
sizeof(dri_name) is 8B on 64Bit systems.The intended operation is coping
the string after '/' from the string `name`.

This bug is not letting to probe any device string >8B hence results in
the testpmd error("No ethernet devices found) on some PMDs.

Cc: Andy Green <andy@warmcat.com>
Cc: Pablo de Lara <pablo.de.lara.guarch@intel.com>

Fixes: fe5f777b538 ("bus/pci: replace strncpy by strlcpy")

Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
---
 drivers/bus/pci/linux/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andy Green May 15, 2018, 10:19 a.m. UTC | #1
On 05/15/2018 06:03 PM, Jerin Jacob wrote:
> sizeof(dri_name) is 8B on 64Bit systems.The intended operation is coping
> the string after '/' from the string `name`.
> 
> This bug is not letting to probe any device string >8B hence results in
> the testpmd error("No ethernet devices found) on some PMDs.

You are right... but...

> Cc: Andy Green <andy@warmcat.com>
> Cc: Pablo de Lara <pablo.de.lara.guarch@intel.com>
> 
> Fixes: fe5f777b538 ("bus/pci: replace strncpy by strlcpy")
> 
> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> ---
>   drivers/bus/pci/linux/pci.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> index a73ee49c2..cd45875b1 100644
> --- a/drivers/bus/pci/linux/pci.c
> +++ b/drivers/bus/pci/linux/pci.c
> @@ -54,7 +54,7 @@ pci_get_kernel_driver_by_path(const char *filename, char *dri_name)
>   
>   	name = strrchr(path, '/');
>   	if (name) {
> -		strlcpy(dri_name, name + 1, sizeof(dri_name));
> +		strlcpy(dri_name, name + 1, strlen(name));

... this fix is no good.  The underlying problem is the length of 
dri_name is not getting passed into this function... it just doesn't 
know how much of dri_name is safe to use.  Telling it to use the 
strlen() of something unrelated is going to make buffer overflows possible.

I sent a patch to the list a few hours ago that amends this function to 
take the allocated length of dri_name, and sets the limit for the 
strlcpy() to that, so no matter what turns up in name it's not possible 
to blow past dri_name allocation.

[dpdk-dev] [PATCH] bus/pci: correct the earlier strlcpy conversion​

-Andy

>   		return 0;
>   	}
>   
>
Jerin Jacob May 15, 2018, 10:31 a.m. UTC | #2
-----Original Message-----
> Date: Tue, 15 May 2018 18:19:19 +0800
> From: Andy Green <andy@warmcat.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, dev@dpdk.org
> CC: thomas@monjalon.net, ferruh.yigit@intel.com, Pablo de Lara
>  <pablo.de.lara.guarch@intel.com>
> Subject: Re: [dpdk-dev] [PATCH] bus/pci: fix driver name string manipulation
> User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
>  Thunderbird/52.7.0
> 
> 
> 
> On 05/15/2018 06:03 PM, Jerin Jacob wrote:
> > sizeof(dri_name) is 8B on 64Bit systems.The intended operation is coping
> > the string after '/' from the string `name`.
> > 
> > This bug is not letting to probe any device string >8B hence results in
> > the testpmd error("No ethernet devices found) on some PMDs.
> 
> You are right... but...
> 
> > Cc: Andy Green <andy@warmcat.com>
> > Cc: Pablo de Lara <pablo.de.lara.guarch@intel.com>
> > 
> > Fixes: fe5f777b538 ("bus/pci: replace strncpy by strlcpy")
> > 
> > Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > ---
> >   drivers/bus/pci/linux/pci.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> > index a73ee49c2..cd45875b1 100644
> > --- a/drivers/bus/pci/linux/pci.c
> > +++ b/drivers/bus/pci/linux/pci.c
> > @@ -54,7 +54,7 @@ pci_get_kernel_driver_by_path(const char *filename, char *dri_name)
> >   	name = strrchr(path, '/');
> >   	if (name) {
> > -		strlcpy(dri_name, name + 1, sizeof(dri_name));
> > +		strlcpy(dri_name, name + 1, strlen(name));
> 
> ... this fix is no good.  The underlying problem is the length of dri_name
> is not getting passed into this function... it just doesn't know how much of
> dri_name is safe to use.  Telling it to use the strlen() of something
> unrelated is going to make buffer overflows possible.

In this case, already there is a check for following in the code. So it is fine
either way.

        path[count] = '\0';
        name = strrchr(path, '/');

> 
> I sent a patch to the list a few hours ago that amends this function to take
> the allocated length of dri_name, and sets the limit for the strlcpy() to
> that, so no matter what turns up in name it's not possible to blow past
> dri_name allocation.
> 
> [dpdk-dev] [PATCH] bus/pci: correct the earlier strlcpy conversion​

I am fine with taking any of the of the patch.  Please improve the patch subject
and bug description in case if you prefer to take your original patch.

> 
> -Andy
> 
> >   		return 0;
> >   	}
> >
Andy Green May 15, 2018, 10:41 a.m. UTC | #3
On 05/15/2018 06:31 PM, Jerin Jacob wrote:
> -----Original Message-----
>> Date: Tue, 15 May 2018 18:19:19 +0800
>> From: Andy Green <andy@warmcat.com>
>> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, dev@dpdk.org
>> CC: thomas@monjalon.net, ferruh.yigit@intel.com, Pablo de Lara
>>   <pablo.de.lara.guarch@intel.com>
>> Subject: Re: [dpdk-dev] [PATCH] bus/pci: fix driver name string manipulation
>> User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
>>   Thunderbird/52.7.0
>>
>>
>>
>> On 05/15/2018 06:03 PM, Jerin Jacob wrote:
>>> sizeof(dri_name) is 8B on 64Bit systems.The intended operation is coping
>>> the string after '/' from the string `name`.
>>>
>>> This bug is not letting to probe any device string >8B hence results in
>>> the testpmd error("No ethernet devices found) on some PMDs.
>>
>> You are right... but...
>>
>>> Cc: Andy Green <andy@warmcat.com>
>>> Cc: Pablo de Lara <pablo.de.lara.guarch@intel.com>
>>>
>>> Fixes: fe5f777b538 ("bus/pci: replace strncpy by strlcpy")
>>>
>>> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
>>> ---
>>>    drivers/bus/pci/linux/pci.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
>>> index a73ee49c2..cd45875b1 100644
>>> --- a/drivers/bus/pci/linux/pci.c
>>> +++ b/drivers/bus/pci/linux/pci.c
>>> @@ -54,7 +54,7 @@ pci_get_kernel_driver_by_path(const char *filename, char *dri_name)
>>>    	name = strrchr(path, '/');
>>>    	if (name) {
>>> -		strlcpy(dri_name, name + 1, sizeof(dri_name));
>>> +		strlcpy(dri_name, name + 1, strlen(name));
>>
>> ... this fix is no good.  The underlying problem is the length of dri_name
>> is not getting passed into this function... it just doesn't know how much of
>> dri_name is safe to use.  Telling it to use the strlen() of something
>> unrelated is going to make buffer overflows possible.
> 
> In this case, already there is a check for following in the code. So it is fine
> either way.
> 
>          path[count] = '\0';
>          name = strrchr(path, '/');

I understand.  But if any of that code changes, the copy can overrun. 
It's more robust if the copy limit is directly referenced to the 
destination size.

>> I sent a patch to the list a few hours ago that amends this function to take
>> the allocated length of dri_name, and sets the limit for the strlcpy() to
>> that, so no matter what turns up in name it's not possible to blow past
>> dri_name allocation.
>>
>> [dpdk-dev] [PATCH] bus/pci: correct the earlier strlcpy conversion​
> 
> I am fine with taking any of the of the patch.  Please improve the patch subject
> and bug description in case if you prefer to take your original patch.

OK.  Or the maintainer is welcome to change the commit title how he 
likes directly.

-Andy

>>
>> -Andy
>>
>>>    		return 0;
>>>    	}
>>>
Thomas Monjalon May 15, 2018, 10:54 a.m. UTC | #4
15/05/2018 12:41, Andy Green:
> On 05/15/2018 06:31 PM, Jerin Jacob wrote:
> >> [dpdk-dev] [PATCH] bus/pci: correct the earlier strlcpy conversion​
> > 
> > I am fine with taking any of the of the patch.  Please improve the patch subject
> > and bug description in case if you prefer to take your original patch.
> 
> OK.  Or the maintainer is welcome to change the commit title how he 
> likes directly.

Andy, the problem is not the title but the bug description I think.

I see that Andrew has just sent a description.
I will use it.

Patch
diff mbox

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index a73ee49c2..cd45875b1 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -54,7 +54,7 @@  pci_get_kernel_driver_by_path(const char *filename, char *dri_name)
 
 	name = strrchr(path, '/');
 	if (name) {
-		strlcpy(dri_name, name + 1, sizeof(dri_name));
+		strlcpy(dri_name, name + 1, strlen(name));
 		return 0;
 	}