[libcamera-devel] [PATCH] android: jpeg: exif: Sanitize ASCII strings with utils::toAscii()

[Umang Jain]

Hi Laurent,

On 10/5/20 9:23 PM, Laurent Pinchart wrote:
> On Mon, Oct 05, 2020 at 04:39:53PM +0100, Kieran Bingham wrote:
>> Hi Umang,
>>
>> On 05/10/2020 14:11, Umang Jain wrote:
>>> Use the newly introduced utils::toAscii() utility to remove all
>>> non-ASCII characters for EXIF_FORMAT_ASCII strings.
>>>
>>> Signed-off-by: Umang Jain <email at uajain.com>
>>> ---
>>>   src/android/jpeg/exif.cpp | 13 +++++++++----
>>>   1 file changed, 9 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
>>> index 3fd5d55..bd528a7 100644
>>> --- a/src/android/jpeg/exif.cpp
>>> +++ b/src/android/jpeg/exif.cpp
>>> @@ -8,6 +8,7 @@
>>>   #include "exif.h"
>>>   
>>>   #include "libcamera/internal/log.h"
>>> +#include "libcamera/internal/utils.h"
>>>   
>>>   using namespace libcamera;
>>>   
>>> @@ -171,15 +172,19 @@ void Exif::setRational(ExifIfd ifd, ExifTag tag, ExifRational item)
>>>   
>>>   void Exif::setString(ExifIfd ifd, ExifTag tag, ExifFormat format, const std::string &item)
>>>   {
>>> -	/* Pad 1 extra byte for null-terminated string in ASCII format. */
>>> -	size_t length = format == EXIF_FORMAT_ASCII ?
>>> -			item.length() + 1 : item.length();
>>> +	size_t length = item.length();
>>> +	std::string str = item;
>>> +	if (format == EXIF_FORMAT_ASCII) {
>>> +		str = utils::toAscii(str);
>>> +		/* Pad 1 extra byte to null-terminate the ASCII string. */
>>> +		length += 1;
> length may have changed after the call to toAscii()
Oops, great catch. Submitted v2.
>
>> This could of course also be
>> 		length++;
>>
>> But += 1 is also quite readable here so I don't mind it staying.
>>
>> Sanitizing the Ascii strings seems to make some sense, especially as we
>> do it elsewhere - so here seems reasonable to me.
>>
>> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>
>>
>>> +	}
>>>   
>>>   	ExifEntry *entry = createEntry(ifd, tag, format, length, length);
>>>   	if (!entry)
>>>   		return;
>>>   
>>> -	memcpy(entry->data, item.c_str(), length);
>>> +	memcpy(entry->data, str.c_str(), length);
>>>   	exif_entry_unref(entry);
>>>   }
>>>