[media] saa7164: add guard bytes around critical buffers to detect failure

If the guard bytes are trampled then we have a memory related problem.

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/saa7164/saa7164-core.c b/drivers/media/video/saa7164/saa7164-core.c
index 624ad3e..e96bbe4 100644 (file)
--- a/drivers/media/video/saa7164/saa7164-core.c
+++ b/drivers/media/video/saa7164/saa7164-core.c
@@ -216,6 +216,7 @@ static void saa7164_work_enchandler(struct work_struct *w)
        struct saa7164_user_buffer *ubuf;
        struct list_head *c, *n;
        int wp, rp, i = 0;
+       u8 *p;
 
        port->last_svc_msecs_diff = port->last_svc_msecs;
        port->last_svc_msecs = jiffies_to_msecs(jiffies);
@@ -262,6 +263,20 @@ static void saa7164_work_enchandler(struct work_struct *w)
                        break;
                }
 
+               p = (u8 *)buf->cpu;
+               if (    (*(p + buf->actual_size + 0) != 0xff) ||
+                       (*(p + buf->actual_size + 1) != 0xff) ||
+                       (*(p + buf->actual_size + 2) != 0xff) ||
+                       (*(p + buf->actual_size + 3) != 0xff) ||
+                       (*(p + buf->actual_size + 0x10) != 0xff) ||
+                       (*(p + buf->actual_size + 0x11) != 0xff) ||
+                       (*(p + buf->actual_size + 0x12) != 0xff) ||
+                       (*(p + buf->actual_size + 0x13) != 0xff) )
+               {
+                       printk(KERN_ERR "buf %p failed guard check\n", buf);
+                       saa7164_dumphex16(dev, p + buf->actual_size - 32, 64);
+               }
+
                if (buf->idx == rp) {
                        /* Found the buffer, deal with it */
                        dprintk(DBGLVL_IRQ, "%s() wp: %d processing: %d\n",
@@ -278,9 +293,12 @@ static void saa7164_work_enchandler(struct work_struct *w)
                                ubuf = list_first_entry(&port->list_buf_free.list,
                                        struct saa7164_user_buffer, list);
 
-                               if (ubuf->actual_size == buf->actual_size)
+                               if (ubuf->actual_size == buf->actual_size) {
                                        memcpy(ubuf->data, buf->cpu,
                                                ubuf->actual_size);
+                               } else {
+                                       printk(KERN_ERR "buf %p actual fails match\n", buf);
+                               }
 
                                /* Requeue the buffer on the free list */
                                ubuf->pos = 0;
@@ -297,7 +315,7 @@ static void saa7164_work_enchandler(struct work_struct *w)
                        /* Ensure offset into buffer remains 0, fill buffer
                         * with known bad data. */
                        saa7164_buffer_zero_offsets(port, rp);
-                       memset(buf->cpu, 0xDE, buf->pci_size);
+                       memset(buf->cpu, 0xff, buf->pci_size);
 
                        break;
                }

diff --git a/drivers/media/video/saa7164/saa7164-encoder.c b/drivers/media/video/saa7164/saa7164-encoder.c
index 5f73ced..c61907d 100644 (file)
--- a/drivers/media/video/saa7164/saa7164-encoder.c
+++ b/drivers/media/video/saa7164/saa7164-encoder.c
@@ -1038,14 +1038,18 @@ static ssize_t fops_read(struct file *file, char __user *buffer,
        saa7164_histogram_update(&port->read_interval,
                port->last_read_msecs_diff);
 
-       if (*pos)
+       if (*pos) {
+               printk(KERN_ERR "%s() ESPIPE\n", __func__);
                return -ESPIPE;
+       }
 
        if (atomic_cmpxchg(&fh->v4l_reading, 0, 1) == 0) {
                if (atomic_inc_return(&port->v4l_reader_count) == 1) {
 
-                       if (saa7164_encoder_initialize(port) < 0)
+                       if (saa7164_encoder_initialize(port) < 0) {
+                               printk(KERN_ERR "%s() EINVAL\n", __func__);
                                return -EINVAL;
+                       }
 
                        saa7164_encoder_start_streaming(port);
                        msleep(200);
@@ -1056,6 +1060,7 @@ static ssize_t fops_read(struct file *file, char __user *buffer,
        if ((file->f_flags & O_NONBLOCK) == 0) {
                if (wait_event_interruptible(port->wait_read,
                        saa7164_enc_next_buf(port))) {
+                               printk(KERN_ERR "%s() ERESTARTSYS\n", __func__);
                                return -ERESTARTSYS;
                }
        }
@@ -1077,8 +1082,10 @@ static ssize_t fops_read(struct file *file, char __user *buffer,
 
                if (copy_to_user(buffer, p, cnt)) {
                        printk(KERN_ERR "%s() copy_to_user failed\n", __func__);
-                       if (!ret)
+                       if (!ret) {
+                               printk(KERN_ERR "%s() EFAULT\n", __func__);
                                ret = -EFAULT;
+                       }
                        goto err;
                }
 
@@ -1087,6 +1094,10 @@ static ssize_t fops_read(struct file *file, char __user *buffer,
                buffer += cnt;
                ret += cnt;
 
+               if (ubuf->pos > ubuf->actual_size) {
+                       printk(KERN_ERR "read() pos > actual, huh?\n");
+               }
+
                if (ubuf->pos == ubuf->actual_size) {
 
                        /* finished with current buffer, take next buffer */
@@ -1109,8 +1120,10 @@ static ssize_t fops_read(struct file *file, char __user *buffer,
                }
        }
 err:
-       if (!ret && !ubuf)
+       if (!ret && !ubuf) {
+               printk(KERN_ERR "%s() EAGAIN\n", __func__);
                ret = -EAGAIN;
+       }
 
        return ret;
 }