[PATCH v4 14/18] staging: media: zoran: calculate the right buffer number for zoran_reap_stat_com

[Corentin Labbe <clabbe@baylibre.com>]

On the case tmp_dcim=1, the index of buffer is miscalculated.
This generate a NULL pointer dereference later.

So let's fix the calcul and add a check to prevent this to reappear.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
---
 drivers/staging/media/zoran/zoran_device.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/zoran/zoran_device.c b/drivers/staging/media/zoran/zoran_device.c
index 5b12a730a229..294e459307c3 100644
--- a/drivers/staging/media/zoran/zoran_device.c
+++ b/drivers/staging/media/zoran/zoran_device.c
@@ -814,7 +814,7 @@ static void zoran_reap_stat_com(struct zoran *zr)
 		if (zr->jpg_settings.tmp_dcm == 1)
 			i = (zr->jpg_dma_tail - zr->jpg_err_shift) & BUZ_MASK_STAT_COM;
 		else
-			i = ((zr->jpg_dma_tail - zr->jpg_err_shift) & 1) * 2 + 1;
+			i = ((zr->jpg_dma_tail - zr->jpg_err_shift) & 1) * 2;
 
 		stat_com = le32_to_cpu(zr->stat_com[i]);
 		if ((stat_com & 1) == 0) {
@@ -826,6 +826,11 @@ static void zoran_reap_stat_com(struct zoran *zr)
 		size = (stat_com & GENMASK(22, 1)) >> 1;
 
 		buf = zr->inuse[i];
+		if (!buf) {
+			spin_unlock_irqrestore(&zr->queued_bufs_lock, flags);
+			pci_err(zr->pci_dev, "No buffer at slot %d\n", i);
+			return;
+		}
 		buf->vbuf.vb2_buf.timestamp = ktime_get_ns();
 
 		if (zr->codec_mode == BUZ_MODE_MOTION_COMPRESS) {
-- 
2.32.0