From: Andy Green <andy@warmcat.com>
To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Cc: dev@dpdk.org, 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
Date: Tue, 15 May 2018 18:41:03 +0800 [thread overview]
Message-ID: <007d01ed-1a2c-ce74-7ce5-b8e71b41b06d@warmcat.com> (raw)
In-Reply-To: <20180515103130.GA14446@jerin>
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;
>>> }
>>>
next prev parent reply other threads:[~2018-05-15 10:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-15 10:03 Jerin Jacob
2018-05-15 10:19 ` Andy Green
2018-05-15 10:31 ` Jerin Jacob
2018-05-15 10:41 ` Andy Green [this message]
2018-05-15 10:54 ` Thomas Monjalon
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