media: v4l2-tpg: prevent the risk of a division by zero

commit e6a3ea83fbe15d4818d01804e904cbb0e64e543b upstream.

As reported by Coverity, the logic at tpg_precalculate_line()
blindly rescales the buffer even when scaled_witdh is equal to
zero. If this ever happens, this will cause a division by zero.

Instead, add a WARN_ON_ONCE() to trigger such cases and return
without doing any precalculation.

Fixes: 63881df94d3e ("[media] vivid: add the Test Pattern Generator")
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
index 182a300e2d445c1bbe7167551f7f0cf6e1addc7b..84f8ca9bf0282f081fda41ad2696ecd918671524 100644 (file)
--- a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
+++ b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
@@ -1639,6 +1639,9 @@ static void tpg_precalculate_line(struct tpg_data *tpg)
        unsigned p;
        unsigned x;
 
+       if (WARN_ON_ONCE(!tpg->src_width || !tpg->scaled_width))
+               return;
+
        switch (tpg->pattern) {
        case TPG_PAT_GREEN:
                contrast = TPG_COLOR_100_RED;