V4L/DVB: gspca - main: Don't use the frame buffer flags

This patch fixes possible race conditions in queue management with SMP:
when a frame was completed, the irq function tried to use the next frame
buffer. At this time, it was possible that the application on an other
processor updated the frame pointer, making the image to point to a bad
buffer.
The patch contains two main changes:
- the image transfer uses the queue indexes which are protected against
  simultaneous memory access,
- the image pointer which is used for image concatenation is only set at
  interrupt level.
Some subdrivers which used the image pointer have been updated.

Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/gspca/cpia1.c b/drivers/media/video/gspca/cpia1.c
index 4b3ea3b4bbbaa90b33c103f09241fb5e53f31611..3747a1dcff5467682bbf8918ec67c7bc0ddf0796 100644 (file)
--- a/drivers/media/video/gspca/cpia1.c
+++ b/drivers/media/video/gspca/cpia1.c
@@ -1765,14 +1765,10 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
                atomic_set(&sd->cam_exposure, data[39] * 2);
                atomic_set(&sd->fps, data[41]);
 
-               image = gspca_dev->image;
-               if (image == NULL) {
-                       gspca_dev->last_packet_type = DISCARD_PACKET;
-                       return;
-               }
-
                /* Check for proper EOF for last frame */
-               if (gspca_dev->image_len > 4 &&
+               image = gspca_dev->image;
+               if (image != NULL &&
+                   gspca_dev->image_len > 4 &&
                    image[gspca_dev->image_len - 4] == 0xff &&
                    image[gspca_dev->image_len - 3] == 0xff &&
                    image[gspca_dev->image_len - 2] == 0xff &&

diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index 2dc7270722f39fd2b584eac85948ae95bcb23482..11b0e3557c1b52eb0323863ee4ace48496ccb81a 100644 (file)
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -315,8 +315,6 @@ static void fill_frame(struct gspca_dev *gspca_dev,
                urb->status = 0;
                goto resubmit;
        }
-       if (gspca_dev->image == NULL)
-               gspca_dev->last_packet_type = DISCARD_PACKET;
        pkt_scan = gspca_dev->sd_desc->pkt_scan;
        for (i = 0; i < urb->number_of_packets; i++) {
 
@@ -428,16 +426,19 @@ void gspca_frame_add(struct gspca_dev *gspca_dev,
 
        PDEBUG(D_PACK, "add t:%d l:%d", packet_type, len);
 
-       /* check the availability of the frame buffer */
-       if (gspca_dev->image == NULL)
-               return;
-
        if (packet_type == FIRST_PACKET) {
-               i = gspca_dev->fr_i;
+               i = atomic_read(&gspca_dev->fr_i);
+
+               /* if there are no queued buffer, discard the whole frame */
+               if (i == atomic_read(&gspca_dev->fr_q)) {
+                       gspca_dev->last_packet_type = DISCARD_PACKET;
+                       return;
+               }
                j = gspca_dev->fr_queue[i];
                frame = &gspca_dev->frame[j];
                frame->v4l2_buf.timestamp = ktime_to_timeval(ktime_get());
                frame->v4l2_buf.sequence = ++gspca_dev->sequence;
+               gspca_dev->image = frame->data;
                gspca_dev->image_len = 0;
        } else if (gspca_dev->last_packet_type == DISCARD_PACKET) {
                if (packet_type == LAST_PACKET)
@@ -460,31 +461,24 @@ void gspca_frame_add(struct gspca_dev *gspca_dev,
        }
        gspca_dev->last_packet_type = packet_type;
 
-       /* if last packet, wake up the application and advance in the queue */
+       /* if last packet, invalidate packet concatenation until
+        * next first packet, wake up the application and advance
+        * in the queue */
        if (packet_type == LAST_PACKET) {
-               i = gspca_dev->fr_i;
+               i = atomic_read(&gspca_dev->fr_i);
                j = gspca_dev->fr_queue[i];
                frame = &gspca_dev->frame[j];
                frame->v4l2_buf.bytesused = gspca_dev->image_len;
                frame->v4l2_buf.flags = (frame->v4l2_buf.flags
                                         | V4L2_BUF_FLAG_DONE)
                                        & ~V4L2_BUF_FLAG_QUEUED;
+               i = (i + 1) % GSPCA_MAX_FRAMES;
+               atomic_set(&gspca_dev->fr_i, i);
                wake_up_interruptible(&gspca_dev->wq);  /* event = new frame */
-               i = (i + 1) % gspca_dev->nframes;
-               gspca_dev->fr_i = i;
-               PDEBUG(D_FRAM, "frame complete len:%d q:%d i:%d o:%d",
-                       frame->v4l2_buf.bytesused,
-                       gspca_dev->fr_q,
-                       i,
-                       gspca_dev->fr_o);
-               j = gspca_dev->fr_queue[i];
-               frame = &gspca_dev->frame[j];
-               if ((frame->v4l2_buf.flags & BUF_ALL_FLAGS)
-                                       == V4L2_BUF_FLAG_QUEUED) {
-                       gspca_dev->image = frame->data;
-               } else {
-                       gspca_dev->image = NULL;
-               }
+               PDEBUG(D_FRAM, "frame complete len:%d",
+                       frame->v4l2_buf.bytesused);
+               gspca_dev->image = NULL;
+               gspca_dev->image_len = 0;
        }
 }
 EXPORT_SYMBOL(gspca_frame_add);
@@ -514,8 +508,8 @@ static int frame_alloc(struct gspca_dev *gspca_dev,
        PDEBUG(D_STREAM, "frame alloc frsz: %d", frsz);
        frsz = PAGE_ALIGN(frsz);
        gspca_dev->frsz = frsz;
-       if (count > GSPCA_MAX_FRAMES)
-               count = GSPCA_MAX_FRAMES;
+       if (count >= GSPCA_MAX_FRAMES)
+               count = GSPCA_MAX_FRAMES - 1;
        gspca_dev->frbuf = vmalloc_32(frsz * count);
        if (!gspca_dev->frbuf) {
                err("frame alloc failed");
@@ -534,11 +528,9 @@ static int frame_alloc(struct gspca_dev *gspca_dev,
                frame->data = gspca_dev->frbuf + i * frsz;
                frame->v4l2_buf.m.offset = i * frsz;
        }
-       gspca_dev->fr_i = gspca_dev->fr_o = gspca_dev->fr_q = 0;
-       gspca_dev->image = NULL;
-       gspca_dev->image_len = 0;
-       gspca_dev->last_packet_type = DISCARD_PACKET;
-       gspca_dev->sequence = 0;
+       atomic_set(&gspca_dev->fr_q, 0);
+       atomic_set(&gspca_dev->fr_i, 0);
+       gspca_dev->fr_o = 0;
        return 0;
 }
 
@@ -776,6 +768,12 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev)
                goto out;
        }
 
+       /* reset the streaming variables */
+       gspca_dev->image = NULL;
+       gspca_dev->image_len = 0;
+       gspca_dev->last_packet_type = DISCARD_PACKET;
+       gspca_dev->sequence = 0;
+
        gspca_dev->usb_err = 0;
 
        /* set the higher alternate setting and
@@ -1591,7 +1589,7 @@ static int vidioc_streamoff(struct file *file, void *priv,
                                enum v4l2_buf_type buf_type)
 {
        struct gspca_dev *gspca_dev = priv;
-       int i, ret;
+       int ret;
 
        if (buf_type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
                return -EINVAL;
@@ -1615,12 +1613,10 @@ static int vidioc_streamoff(struct file *file, void *priv,
        gspca_stream_off(gspca_dev);
        mutex_unlock(&gspca_dev->usb_lock);
 
-       /* empty the application queues */
-       for (i = 0; i < gspca_dev->nframes; i++)
-               gspca_dev->frame[i].v4l2_buf.flags &= ~BUF_ALL_FLAGS;
-       gspca_dev->fr_i = gspca_dev->fr_o = gspca_dev->fr_q = 0;
-       gspca_dev->last_packet_type = DISCARD_PACKET;
-       gspca_dev->sequence = 0;
+       /* empty the transfer queues */
+       atomic_set(&gspca_dev->fr_q, 0);
+       atomic_set(&gspca_dev->fr_i, 0);
+       gspca_dev->fr_o = 0;
        ret = 0;
 out:
        mutex_unlock(&gspca_dev->queue_lock);
@@ -1697,7 +1693,7 @@ static int vidioc_s_parm(struct file *filp, void *priv,
        int n;
 
        n = parm->parm.capture.readbuffers;
-       if (n == 0 || n > GSPCA_MAX_FRAMES)
+       if (n == 0 || n >= GSPCA_MAX_FRAMES)
                parm->parm.capture.readbuffers = gspca_dev->nbufread;
        else
                gspca_dev->nbufread = n;
@@ -1800,21 +1796,17 @@ out:
 static int frame_wait(struct gspca_dev *gspca_dev,
                        int nonblock_ing)
 {
-       struct gspca_frame *frame;
-       int i, j, ret;
+       int i, ret;
 
        /* check if a frame is ready */
        i = gspca_dev->fr_o;
-       j = gspca_dev->fr_queue[i];
-       frame = &gspca_dev->frame[j];
-
-       if (!(frame->v4l2_buf.flags & V4L2_BUF_FLAG_DONE)) {
+       if (i == atomic_read(&gspca_dev->fr_i)) {
                if (nonblock_ing)
                        return -EAGAIN;
 
                /* wait till a frame is ready */
                ret = wait_event_interruptible_timeout(gspca_dev->wq,
-                       (frame->v4l2_buf.flags & V4L2_BUF_FLAG_DONE) ||
+                       i != atomic_read(&gspca_dev->fr_i) ||
                        !gspca_dev->streaming || !gspca_dev->present,
                        msecs_to_jiffies(3000));
                if (ret < 0)
@@ -1823,11 +1815,7 @@ static int frame_wait(struct gspca_dev *gspca_dev,
                        return -EIO;
        }
 
-       gspca_dev->fr_o = (i + 1) % gspca_dev->nframes;
-       PDEBUG(D_FRAM, "frame wait q:%d i:%d o:%d",
-               gspca_dev->fr_q,
-               gspca_dev->fr_i,
-               gspca_dev->fr_o);
+       gspca_dev->fr_o = (i + 1) % GSPCA_MAX_FRAMES;
 
        if (gspca_dev->sd_desc->dq_callback) {
                mutex_lock(&gspca_dev->usb_lock);
@@ -1836,7 +1824,7 @@ static int frame_wait(struct gspca_dev *gspca_dev,
                        gspca_dev->sd_desc->dq_callback(gspca_dev);
                mutex_unlock(&gspca_dev->usb_lock);
        }
-       return j;
+       return gspca_dev->fr_queue[i];
 }
 
 /*
@@ -1941,15 +1929,9 @@ static int vidioc_qbuf(struct file *file, void *priv,
        }
 
        /* put the buffer in the 'queued' queue */
-       i = gspca_dev->fr_q;
+       i = atomic_read(&gspca_dev->fr_q);
        gspca_dev->fr_queue[i] = index;
-       if (gspca_dev->fr_i == i)
-               gspca_dev->image = frame->data;
-       gspca_dev->fr_q = (i + 1) % gspca_dev->nframes;
-       PDEBUG(D_FRAM, "qbuf q:%d i:%d o:%d",
-               gspca_dev->fr_q,
-               gspca_dev->fr_i,
-               gspca_dev->fr_o);
+       atomic_set(&gspca_dev->fr_q, (i + 1) % GSPCA_MAX_FRAMES);
 
        v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED;
        v4l2_buf->flags &= ~V4L2_BUF_FLAG_DONE;
@@ -2005,7 +1987,7 @@ static int read_alloc(struct gspca_dev *gspca_dev,
 static unsigned int dev_poll(struct file *file, poll_table *wait)
 {
        struct gspca_dev *gspca_dev = file->private_data;
-       int i, ret;
+       int ret;
 
        PDEBUG(D_FRAM, "poll");
 
@@ -2023,11 +2005,9 @@ static unsigned int dev_poll(struct file *file, poll_table *wait)
        if (mutex_lock_interruptible(&gspca_dev->queue_lock) != 0)
                return POLLERR;
 
-       /* check the next incoming buffer */
-       i = gspca_dev->fr_o;
-       i = gspca_dev->fr_queue[i];
-       if (gspca_dev->frame[i].v4l2_buf.flags & V4L2_BUF_FLAG_DONE)
-               ret = POLLIN | POLLRDNORM;      /* something to read */
+       /* check if an image has been received */
+       if (gspca_dev->fr_o != atomic_read(&gspca_dev->fr_i))
+               ret = POLLIN | POLLRDNORM;      /* yes */
        else
                ret = 0;
        mutex_unlock(&gspca_dev->queue_lock);

diff --git a/drivers/media/video/gspca/gspca.h b/drivers/media/video/gspca/gspca.h
index 453e43d66a833731ba84db5e876c15338d151bf7..17e55580631ed7634156db373287e9e4b49cadb0 100644 (file)
--- a/drivers/media/video/gspca/gspca.h
+++ b/drivers/media/video/gspca/gspca.h
@@ -178,11 +178,11 @@ struct gspca_dev {
        u8 *image;                              /* image beeing filled */
        __u32 frsz;                             /* frame size */
        u32 image_len;                          /* current length of image */
-       char nframes;                           /* number of frames */
-       char fr_i;                              /* frame being filled */
-       char fr_q;                              /* next frame to queue */
-       char fr_o;                              /* next frame to dequeue */
+       atomic_t fr_q;                          /* next frame to queue */
+       atomic_t fr_i;                          /* frame being filled */
        signed char fr_queue[GSPCA_MAX_FRAMES]; /* frame queue */
+       char nframes;                           /* number of frames */
+       u8 fr_o;                                /* next frame to dequeue */
        __u8 last_packet_type;
        __s8 empty_packet;              /* if (-1) don't check empty packets */
        __u8 streaming;

diff --git a/drivers/media/video/gspca/m5602/m5602_core.c b/drivers/media/video/gspca/m5602/m5602_core.c
index 0c4ad5a5642ac0fca574476e8e95135a9788c981..b073d66acd04a7ff5c32ad2d407c0ad5da72353a 100644 (file)
--- a/drivers/media/video/gspca/m5602/m5602_core.c
+++ b/drivers/media/video/gspca/m5602/m5602_core.c
@@ -307,11 +307,6 @@ static void m5602_urb_complete(struct gspca_dev *gspca_dev,
        } else {
                int cur_frame_len;
 
-               if (gspca_dev->image == NULL) {
-                       gspca_dev->last_packet_type = DISCARD_PACKET;
-                       return;
-               }
-
                cur_frame_len = gspca_dev->image_len;
                /* Remove urb header */
                data += 4;

diff --git a/drivers/media/video/gspca/ov534.c b/drivers/media/video/gspca/ov534.c
index 84c9b8dbded67d2139a2917f647bba3b15d5abf0..96cb3a97658101aa4d496596e2b2658c20b1c0dc 100644 (file)
--- a/drivers/media/video/gspca/ov534.c
+++ b/drivers/media/video/gspca/ov534.c
@@ -988,8 +988,6 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
                /* If this packet is marked as EOF, end the frame */
                } else if (data[1] & UVC_STREAM_EOF) {
                        sd->last_pts = 0;
-                       if (gspca_dev->image == NULL)
-                               goto discard;
                        if (gspca_dev->image_len + len - 12 !=
                            gspca_dev->width * gspca_dev->height * 2) {
                                PDEBUG(D_PACK, "wrong sized frame");

diff --git a/drivers/media/video/gspca/pac7302.c b/drivers/media/video/gspca/pac7302.c
index 88cc03bb3f940e7a6e0b6e9cc8243c74fa0671fe..a66df07d7625668c485660d807c9dea2549bdee2 100644 (file)
--- a/drivers/media/video/gspca/pac7302.c
+++ b/drivers/media/video/gspca/pac7302.c
@@ -835,12 +835,6 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
        if (sof) {
                int n, lum_offset, footer_length;
 
-               image = gspca_dev->image;
-               if (image == NULL) {
-                       gspca_dev->last_packet_type = DISCARD_PACKET;
-                       return;
-               }
-
                /* 6 bytes after the FF D9 EOF marker a number of lumination
                   bytes are send corresponding to different parts of the
                   image, the 14th and 15th byte after the EOF seem to
@@ -856,7 +850,9 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
                } else {
                        gspca_frame_add(gspca_dev, INTER_PACKET, data, n);
                }
-               if (gspca_dev->last_packet_type != DISCARD_PACKET
+
+               image = gspca_dev->image;
+               if (image != NULL
                 && image[gspca_dev->image_len - 2] == 0xff
                 && image[gspca_dev->image_len - 1] == 0xd9)
                        gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);

diff --git a/drivers/media/video/gspca/pac7311.c b/drivers/media/video/gspca/pac7311.c
index 5568c41a296c179d25b696cf0ec1cf6e5477e5f4..1cb7e99e92bde439fa7d65d3c7d910d7d624180c 100644 (file)
--- a/drivers/media/video/gspca/pac7311.c
+++ b/drivers/media/video/gspca/pac7311.c
@@ -630,12 +630,6 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
        if (sof) {
                int n, lum_offset, footer_length;
 
-               image = gspca_dev->image;
-               if (image == NULL) {
-                       gspca_dev->last_packet_type = DISCARD_PACKET;
-                       return;
-               }
-
                /* 6 bytes after the FF D9 EOF marker a number of lumination
                   bytes are send corresponding to different parts of the
                   image, the 14th and 15th byte after the EOF seem to
@@ -651,7 +645,8 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
                } else {
                        gspca_frame_add(gspca_dev, INTER_PACKET, data, n);
                }
-               if (gspca_dev->last_packet_type != DISCARD_PACKET
+               image = gspca_dev->image;
+               if (image != NULL
                 && image[gspca_dev->image_len - 2] == 0xff
                 && image[gspca_dev->image_len - 1] == 0xd9)
                        gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);

diff --git a/drivers/media/video/gspca/sonixb.c b/drivers/media/video/gspca/sonixb.c
index 4989a2c779e567f1ac64d189cd82e9e2660c52be..204bb3af455999b4733c41383c8db9e61f4c67dc 100644 (file)
--- a/drivers/media/video/gspca/sonixb.c
+++ b/drivers/media/video/gspca/sonixb.c
@@ -1254,10 +1254,6 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
                int used;
                int size = cam->cam_mode[gspca_dev->curr_mode].sizeimage;
 
-               if (gspca_dev->image == NULL) {
-                       gspca_dev->last_packet_type = DISCARD_PACKET;
-                       return;
-               }
                used = gspca_dev->image_len;
                if (used + len > size)
                        len = size - used;

diff --git a/drivers/media/video/gspca/vc032x.c b/drivers/media/video/gspca/vc032x.c
index 0a7d1e0866d20a98f5edd9c54903b1ee2f1721ef..82be16938458165ef24a1260f3c6d57628968b14 100644 (file)
--- a/drivers/media/video/gspca/vc032x.c
+++ b/drivers/media/video/gspca/vc032x.c
@@ -3728,10 +3728,6 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
        if (sd->bridge == BRIDGE_VC0321) {
                int size, l;
 
-               if (gspca_dev->image == NULL) {
-                       gspca_dev->last_packet_type = DISCARD_PACKET;
-                       return;
-               }
                l = gspca_dev->image_len;
                size = gspca_dev->frsz;
                if (len > size - l)