media: v4l2-tpg: fix kernel oops when enabling HFLIP and OSD

When the OSD is on (i.e. vivid displays text on top of the test pattern), and
you enable hflip, then the driver crashes.

The cause turned out to be a division of a negative number by an unsigned value.
You expect that -8 / 2U would be -4, but in reality it is 2147483644 :-(

Fixes: 3e14e7a82c1ef ("vivid-tpg: add hor/vert downsampling support to tpg_gen_text")
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: <stable@vger.kernel.org>      # for v4.1 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
index 76b125ebee6dea5aa6285a7c9f1b74f7cfaed2de..fa483b95bc5a996a4a8bb3fe737a32c791cab5bd 100644 (file)
--- a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
+++ b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
@@ -1801,7 +1801,7 @@ typedef struct { u16 __; u8 _; } __packed x24;
                                pos[7] = (chr & (0x01 << 0) ? fg : bg); \
                        } \
        \
-                       pos += (tpg->hflip ? -8 : 8) / hdiv;    \
+                       pos += (tpg->hflip ? -8 : 8) / (int)hdiv;       \
                }       \
        }       \
 } while (0)