[Spice-devel] [PATCH spice-server v2] red-parse-qxl: Fix QUIC images from QXL

[Frediano Ziglio]

> 
> Hi Frediano,
> 
> On 7/23/19 11:21 PM, Frediano Ziglio wrote:
> > The decoding is wrong, the Red and QXL structures are different so
> > code is not doing what is expected. red-parse-qxl translate from QXL
> > to Red structures, red-record-qxl saves Red structure to file,
> > red-replay-qxl is supposed to read from file into QXL directly.
> > 
> > If a Quic image is stored inside QXL memory the layout of the QXLImage
> > in memory is:
> > - QXLImageDescriptor
> > - QXLQUICData
> > - QXLDataChunk
> > - first chunk data
> > and all remaining data in linked QXLDataChunk.
> > red_replay_image was reading the image as data was all contained in
> > QXLImage->quic.data however "data" shoule store the first QXLDataChunk
> 
> shoule -> should
> 

I'll fix, thanks

> > followed by QXLDataChunk data.
> > Use proper base_size calling red_replay_data_chunks in order to
> > initialise the image with the first data chunk correctly.
> 
> I like this patch better then the first one.
> 
> 
> 
> > 
> > Not easy to reproduce, the only driver is XDDM which means Windows XP
> > or similars, I got no recording with such images.
> > 
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > ---
> >   server/red-replay-qxl.c | 17 ++++++++++-------
> >   1 file changed, 10 insertions(+), 7 deletions(-)
> > 
> > Changes v1:
> > - realloc the buffer inside read_binary with the proper size.
> >    The proper size if not available in red_replay_image.
> 
> Can we not just fix the above without moving the realloc call ?
> Before only QUIC memory (which was malloc'ed) was realloc'ed.
> With this other memory may be realloced.

I checked all calls, only for QUIC the initial pointer is NULL
so it will get reallocated.

> 
> Allocate more memory (add sizeof(QXLDataChunk))
>     qxl = replay_realloc(replay, qxl, sizeof(QXLImageDescriptor)
>                          + sizeof(QXLQUICData)
>                          + sizeof(QXLDataChunk)
>                          + qxl->quic.data_size);
> 

No, I rather prefer patch version 1 instead. The replay code should
attempt to allocate memory more like drivers. This will also help
using sanitizer tools. In this specific case allocating a larger
buffer will avoid some potential buffer overflow check.

Looking more at the code I noted that in many places the "header"
(information before chunks) are read into temporary variables
then raw data is allocated with the structure than the structure
header is filled (like red_replay_clip_rects for instance,
another more complicated one is red_replay_cursor).
The exception is red_replay_image where the "qxl" (in this case
a QXLImage type) is allocated at the beginning. One difference
between bitmap and quic is that "data" in QXLBitmap is a
QXLPHYSICAL, not a uint8_t[0].

> Call red_replay_data_chunks as you do in this patch
> Call red_replay_data_chunks_free as you do in this patch.
> 

Surely the offset is wrong, is expected to be the offset of raw
data to write.

> Uri.
> 
> > 
> > diff --git a/server/red-replay-qxl.c b/server/red-replay-qxl.c
> > index 674feae2f..1f1bd8c1d 100644
> > --- a/server/red-replay-qxl.c
> > +++ b/server/red-replay-qxl.c
> > @@ -114,6 +114,9 @@ static inline void replay_free(SpiceReplay *replay,
> > void *mem)
> >   
> >   static inline void *replay_realloc(SpiceReplay *replay, void *mem, size_t
> >   n_bytes)
> >   {
> > +    if (mem == NULL) {
> > +        return replay_malloc(replay, n_bytes);
> > +    }
> >       GList *elem = g_list_find(replay->allocated, mem);
> >       elem->data = g_realloc(mem, n_bytes);
> >       return elem->data;
> > @@ -231,9 +234,7 @@ static replay_t read_binary(SpiceReplay *replay, const
> > char *prefix, size_t *siz
> >           return REPLAY_ERROR;
> >       }
> >   
> > -    if (*buf == NULL) {
> > -        *buf = replay_malloc(replay, *size + base_size);
> > -    }
> > +    *buf = replay_realloc(replay, *buf, *size + base_size);
> >   #if 0
> >       {
> >           int num_read = fread(*buf + base_size, *size, 1, fd);
> > @@ -497,9 +498,9 @@ static QXLImage *red_replay_image(SpiceReplay *replay,
> > uint32_t flags)
> >           if (replay->error) {
> >               return NULL;
> >           }
> > -        qxl = replay_realloc(replay, qxl, sizeof(QXLImageDescriptor) +
> > sizeof(QXLQUICData) +
> > -                             qxl->quic.data_size);
> > -        size = red_replay_data_chunks(replay, "quic.data",
> > (uint8_t**)&qxl->quic.data, 0);
> > +        size = red_replay_data_chunks(replay, "quic.data",
> > (uint8_t**)&qxl,
> > +                                      sizeof(QXLImageDescriptor) +
> > sizeof(QXLQUICData) +
> > +                                      sizeof(QXLDataChunk));
> >           spice_assert(size == qxl->quic.data_size);
> >           break;
> >       default:
> > @@ -526,7 +527,9 @@ static void red_replay_image_free(SpiceReplay *replay,
> > QXLPHYSICAL p, uint32_t f
> >       case SPICE_IMAGE_TYPE_SURFACE:
> >           break;
> >       case SPICE_IMAGE_TYPE_QUIC:
> > -        red_replay_data_chunks_free(replay, qxl, 0);
> > +        red_replay_data_chunks_free(replay, qxl,
> > +                                    sizeof(QXLImageDescriptor) +
> > sizeof(QXLQUICData) +
> > +                                    sizeof(QXLDataChunk));
> >           qxl = NULL;
> >           break;
> >       default:
> >